Topics on this page:
- General Guidelines
- Insect Pests in NY State
- White Grubs
- Weevils
- Caterpillars
- Chinch Bugs
- Ants
- Exotic Crane Flies
General Guidelines
The most effective and efficient pest management programs include (1) diagnosis – correct identification of the insect(s) involved (i.e., who or what are the culprits behind the problem), (2) decision-making – a systematic process to decide if control is necessary (i.e., whether the situation requires a response), and (3) intervention – selecting, targeting and integrating the most appropriate control tactics (i.e., when and where to apply a control in concert with other management techniques). Navigating these stages toward improved pest management will also depend on how well we understand natural history, i.e., the associations among insects, the grasses they feed on, and the overall turfgrass habitat.
Most of the insect pests of turfgrass conduct some stage of their life underground. This poses challenges for their management because of how difficult it is to monitor, interpret and manipulate interactions that are being played out below the soil surface. Compared to above-ground foliar feeding insects, below-ground root feeding insects are harder to monitor and the products used to control them are harder to accurately deliver.
Another challenge for insect pest management is the number of exotic pests that affect turfgrass. Unintentionally introduced to the Northeast U.S., these species have arrived without the natural enemies, competitors or other factors that might have kept their populations in check across their native regions. As a result, there is great potential for outbreaks and damaging infestations. Finally, pest management in turf is also challenging because there are few non-chemical control options that offer reliable alternatives, and because the availability of chemical options is continually changing due to restrictions and market-driven alterations.
In this section on insect management we offer a general overview of the six major insect pest complexes that affect turfgrass systems in NY State such as home lawns, recreational areas, sports fields, golf courses and sod farms. We highlight aspects of turf insect biology, ecology and behavior that are important for understanding their impact as pests and for choosing and applying the most appropriate control tactics. Because this is only a general summary, we include links to additional information.
Insect Pests in NY State
There are some 17 insects that can cause serious injury to turfgrass in NY State belonging to six general complexes: (1) white grubs, (2) weevils, (3) chinch bugs, (4) caterpillars, (5) ants and (6) leatherjackets. White grubs are scarab beetle larvae that live in the soil where they feed on grass roots or otherwise disrupt the rooting zone. Weevil larvae begin as stem borers, then crown feeders, and then as adults they become foliage feeders. Chinch bugs are small, fast-moving sucking insects that live at the soil surface. Caterpillars include black cutworms, sod webworms, and fall armyworms that are primarily active at the soil surface where they feed on above-ground foliage. Ants are relevant when their nests disrupt the surface of the ground. Leatherjackets are the soil-dwelling larvae of crane flies that injure grass both above- and below-ground. The injury caused by these insects can be difficult to differentiate from each other and from certain plant diseases. Nevertheless, control decisions must be based on a correct identification of the insect pest, which means recognizing the injury and knowing how to identify the insect complex and insect species involved. Diagnosis is fundamental because the timing and type of control tactics will depend on the particular species involved, and moreover because chemical control products have labels specific to particular groups of insects. A misdiagnosis means that applicators will not be in full compliance.
White Grubs
Description. White grubs are the larval, or immature, stages of scarab beetles, constituting the most diverse, widespread and damaging group of turf pests in the Northeast U.S. In NY these include four native species (black turfgrass ataenius, green June beetle, May or June beetles, northern masked chafer) and four introduced species (Asiatic garden beetle, European chafer, Japanese beetle, Oriental beetle). While this pest complex occurs across the entire state, the most prevalent species at any one site will vary considerably. Up to four species might occupy the same patch of turf, but the composition and relative abundance of those species will depend on local conditions due to diverging habitat preferences. For instance, Japanese beetles may be more prevalent in irrigated turf such as golf course fairways, while European chafer might be more prevalent in non-irrigated rough. The green June beetle is an exception to widespread occurrence as it is not known outside of southeastern NY.
Natural history. Larvae have well-developed mandibles for chewing on grass roots. The younger larvae may ingest a high proportion of organic material in addition to feeding on fibrous roots. All cool season grasses are susceptible, as well as some species of forage, field and nursery crops. While the adults of some species feed and are damaging to ornamental plants in their own right (e.g., Japanese beetle, Asiatic garden beetle), the adults of other species may not feed at all (e.g., European chafer). No adults feed directly on turfgrass.
Larvae are truly subterranean, moving horizontally through the soil to track food resources and moving vertically in response to drought and temperature. Adults are generally strong fliers, mobilizing to locate mates and egg-laying sites. Because of this, having a lot of adults does not necessarily translate to a lot of grubs. Local control of adult populations will not solve grub problems, nor will local control of grub populations solve adult problems (e.g., Japanese beetle feeding on ornamentals).
Adults of most species rely on female-produced pheromones to attract males for mating. One exception is the European chafer. Males and females of this species aggregate at dusk around prominent trees, vegetation or structures to find mates as they apparently do not use long-distance pheromones. Adult females lay eggs within the top 8 inches of soil, either singly or in small groups. After egg hatch, development proceeds through three larval instars, then prepupa, pupa and adult.
In NY, most species complete one generation a year and overwinter as third instars. As winter approaches, larvae descend to stay below the frost line, and ascend in spring as the frost line recedes. They descend once more for pupation. It is the prepupa that fashions the earthen cell in which the pupa resides until the adult emerges and crawls to the surface. Corresponding to its small size, the black turfgrass ataenius can complete two generations a year and overwinters as an adult. The inverse is true for the large May or June beetle grubs, which may require 2-3 years to complete a single generation.
Most damage is attributed to the large third instar due to extensive pruning (chewing) of the roots at the soil-thatch interface. This kind of injury disrupts water and nutrient flow and, if accompanied by drought stress, the grass will quickly die. High populations can kill extensive areas of turf. Unlike other species, larvae of the green June beetle cause damage by their active tunneling through the root zone, not by direct feeding on roots. Most of their nutrition is obtained by ingesting soil organic matter rather than living roots.
Diagnosis. Larvae are “C”-shaped, with six legs, and well-developed mandibles attached to a defined head capsule. The eight species that occur in NY can be differentiated based on two characters of the abdomen: the raster pattern and the anal slit. The raster pattern is the specific arrangement of hairs, spines and bare patches on the ventral surface of last abdominal segment. The anal slit can be straight or “Y”-shaped. With practice and the help of a hand lens, these features can be distinguished in the field at least for the larger third instars. These two characters are definitive for identifying turf-infesting grub species in NY. More information can be found at ohioline.osu.edu/factsheet/hyg-2510.
When turf is heavily damaged it will feel spongy, not firm, underfoot. It will peel back from the soil like a carpet because the root system has been disrupted or devoured. Above ground, there will be thinning, increased susceptibility to drought and ultimately increased susceptibility to weed invasion. If grub populations do not cause visible damage, then their predators might. The grubbing activities of vertebrates like raccoons, skunks and moles can be highly problematic. It is common that indirect grubbing damage is more troublesome than direct grub damage.
If your goal is to monitor the activity of adults in anticipation of a preventive application around the time of egg hatch, Japanese beetles can be monitored with vane traps (baited with a pheromone and floral lure), European chafer by observing mating swarms, and Asiatic garden beetle by nocturnal sweeping of the grass with an insect net or by its attraction to lights or light traps. More often, however, it is the damaging larval stage that has to be monitored in support of decision-making. To detect larvae or assess their abundance, you have to dig. Unlike certain other turf insects such as caterpillars, disclosing solutions will not force white grubs to the surface. Use a golf course cup cutter, bulb planter, or shovel to examine soil cores for grubs in the root zone. Depending on the size of the species, eggs and first instars are relatively difficult to find, while second and third instars are relatively easy to pick out of the soil.
Decision-making. The potential for future damage can be predicted by sampling for grubs that have not yet caused significant injury. The best time to sample is early August in southeastern NY and mid-August upstate. Egg hatch and grub development, however, may be delayed by cool or dry weather and may also vary from species to species. A sampling scheme should be based on identified problem areas, susceptible areas, and areas that otherwise require better protection (e.g., front lawns, fairways). High priority and high risk areas should be sampled more completely to reduce the chances of overlooking a damaging infestation.
| Table 6.2.2. White grub treatment thresholds | ||
| Number of grubs per | ||
| Species | sq. ft. | core1 |
| Asiatic garden beetle | 18-20 | 2 |
| Black turfgrass ataenius | 30-50 | 3-5 |
| European chafer | 5-8 | Any |
| Green June beetle | 5 | Any |
| Japanese beetle | 8-10 | Any |
| Oriental beetle | 8 | Any |
| Northern masked chafer | 8-12 | Any |
| May and June beetle | 3-4 | Any |
| 14.25-inch diameter soil core of the standard golf course cup cutter | ||
Thresholds have been established as general guidelines for treatment (Table 6.2.2). If several areas are at or above the threshold, intervention may be warranted. Remember, turfgrass that receives sufficient water and has a healthy root system will tolerate higher numbers of grubs than the suggested thresholds. Extensive research in upstate NY shows that insecticide treatments are needed only 20% of the time on home lawns and golf course fairways. In other words, if the decision-making process is bypassed by the consistent use of an early season preventive insecticide, the application may have been unnecessary four times out of five.
Intervention – Cultural control. There is no specific host plant resistance among turf grasses to white grubs. It is therefore not possible to select a grass that eliminates grub problems. Kentucky bluegrass and creeping bentgrass, however, have a spreading growth habit that is beneficial for filling in bare patches caused by grubs. Endophyte-enhanced grasses (e.g., some perennial ryegrass and tall fescue) may be more tolerant of drought stress and recover more quickly from grub damage even though they do not confer resistance per se. Soil moisture and fertility affect the expression of damage by white grubs. Actively growing turf with a good root system may tolerate populations up to 50% higher than treatment thresholds without showing signs of injury. The recovery of grub-damaged turf can be hastened with autumn fertilization. A high-nitrogen application in the spring, however, is detrimental because it weakens the grass by encouraging shoot development without a good root system. Counteract root loss with regular watering and counteract thinning of the stand with overseeding.
Intervention – Chemical control. There are two basic insecticidal approaches to managing white grubs. One is to make a preventive summer application of a slow-acting and long-lasting material, like chlorantraniliprole or imidacloprid, that will prevent subsequent infestations. The second is to wait until mid-August, after egg hatch, and sample for the presence, abundance and distribution of grubs. Areas with populations above threshold levels can be spot treated with a curative insecticide. Data support that imidacloprid can still be effective if used in August. Trichlorfon is a fast-acting, short-lived insecticide that is usually effective in both September and October. However, practitioners should consider the relatively high EIQ of trichlorfon when selecting a treatment strategy. Entomopathogenic nematodes are an alternative curative treatment that can be considered, and are discussed later in this chapter.
The use of a preventive insecticide may be warranted in areas that consistently suffer damaging grub populations, or in risk-adverse situations with high value or high priority turf. The advantages of this approach are (1) the available chemistries have a relatively low EIQ, mammalian toxicity and low rate of active ingredient, (2) a fairly forgiving window of application, (3) if the application fails, other alternatives are available as a late season backup, and (4) no scouting is required. One drawback of this approach is that applications are made too early in the season to scout for grubs. Contrary to best IPM practices, this means that population levels cannot be assessed and compared to damage thresholds for decision-making. A second drawback is that insecticides with longer residuals will also have longer windows of exposure to non-target fauna, which have a role in the natural regulation of pest populations and other beneficial processes including thatch decomposition.
In contrast, use of a curative insecticide can be based on known populations. The specific advantages are that (1) scouting can be used to assess population levels, locations, and species present, (2) intervention decisions can be made based on thresholds, (3) spot treatments can be made over smaller areas, and (4) the fast-acting insecticide, trichlorfon, degrades rapidly. Aside from the labor and cost of scouting, a main drawback of this approach is that there is usually no second chance if the application fails. Another drawback is that trichlorfon has relatively high EIQ, mammalian toxicity and rate of active ingredient.
Curative spring treatments for grub control are not recommended. Although grubs are feeding vigorously at that time of year between overwintering and pupation, the feeding time is relatively short, the grubs are typically as large as they are going to get and are very tolerant of insecticides. In addition, most damage has already occurred and the spring flush in grass growth can usually compensate for grub damage. Regardless of approach, the goal of treatment is never to eradicate completely, but to reduce the population below damage thresholds.
Imidacloprid is a broad-spectrum, long-residual insecticide. This compound is widely relied upon for white grub control in commercial turfgrass. It mostly functions as a systemic so it should be well watered in to reach the roots where it will be taken up by the plant after an activation period. The optimal time to use imidacloprid is at the time of egg laying and egg hatch. Nevertheless, its long-residual gives it a relatively forgiving window of application, from early June to mid-August. While largely used preventively, before scouting is possible, recent research shows that it may be effective against Japanese beetle as late as second instar. Because this developmental stage can be scouted, it opens opportunities to use imidacloprid as a curative. This approach might be suitable if scouting reveals a previously undetected and widespread infestation that is predominately second instar Japanese beetle. In this case, imidacloprid would be a viable option to pursue before a widespread application of a curative alternative. But unless a manager has a good understanding of the timing and potential asynchrony of population development (e.g., Japanese beetle can lay eggs over a period of more than two months), caution should prevail.
All commercial applications of imidacloprid products are restricted-use statewide in NY. In addition, the sale, use, and distribution of consumer products are not allowed in Nassau, Suffolk, Kings or Queens Counties.
Chlorantraniliprole is a broad-spectrum and long-residual insecticide. It can be applied as soon as early April for preventive control, and in August and possibly early September for early curative control. Later season applications may require the high label rate for effective control of second instar larvae. All species of white grubs are susceptible to this insecticide. There is also proven efficacy against many of the other turf-infesting insects in NY. Given its long-residual activity, season long control is probable against white grubs and possible against other insect pests. Subsequent infestations of caterpillars, billbugs, annual bluegrass weevils and European crane flies might be suppressed in chlorantraniliprole-treated turf. When feasible, use scouting to determine whether insecticide applications against those other pest species might be withheld.
Trichlorfon is a fast-acting, short-residual insecticide recommended for curative spot treatments. Trichlorfon is highly soluble and penetrates the thatch layer better than most products. It has an extremely short period of residual activity (7-10 days) and a reduced half-life in alkaline soils. This product is recommended as a late-season curative and should be applied after the grubs have been located, up to as late as mid-September. It should be noted that trichlorfon has a relatively high EIQ, and that carbaryl is the only alternative to trichlorfon for late season and fast-acting control.
Intervention – Biological control. Three biological control agents are commercially available for management of white grubs in turf: entomopathogenic nematodes, entomopathogenic fungi, and the bacteria that cause milky spore disease. Nevertheless, all alternatives have relatively poor or inconsistent results in the field. Therefore, while turfgrass managers might experiment with these products, they should not rely on them for grub management in high-priority areas. They may also be better than nothing in areas where cultural management is insufficient and chemical treatments are either not desired or not allowed.
Entomopathogenic nematodes. Entomopathogenic nematodes can be effective parasites of white grubs. Although they are sometimes as effective as chemical insecticides in laboratory trials, field results are inconsistent and failures are common. Reasons for poor field results include insufficient water at time of application, improper selection of nematode species, improper storage and handling of the nematodes, and unsuitable environmental conditions such as high soil compaction.
Nematodes work in concert with a mutualistic bacterium that they carry in their guts. The infective juvenile stage of nematodes lives freely in the soil; when the juveniles encounter a suitable insect host, they enter through natural openings (e.g., mouth, spiracle or anus) or are sometimes able to penetrate the insect’s cuticle. Inside the host, the nematodes travel to the gut and deliver the lethal bacteria that they vectored inside. The bacteria multiply rapidly, releasing a toxin that kills the host in 1-2 days. The nematodes also multiply inside the host until resources are depleted. At that point, a new generation of infective juveniles exits the cadaver to search for another host in the soil.
Among the available commercial isolates of nematodes, Heterorhabditis bacteriophora is the species recommended for the management of white grubs, however, Steinernema feltiae may also prove effective in porous, sandy sites. S. glaseri are also effective but may not be available commercially. They should be applied while grubs are still young and most susceptible and before they have caused significant damage. Follow sampling suggestions above, and apply nematodes in areas where high populations have been confirmed. Many types of pesticide sprayers can be used. Use low pressure (< 300 psi), and remove any screens finer than 50 mesh. A hose-end sprayer or watering can is ideal for small-scale applications. Apply a minimum rate of 1 billion nematodes per acre, regardless of the manufacturer’s directions.
Because nematodes are harmed by ultraviolet light, they should be applied at dusk or on a cloudy, rainy day. The nematodes use the thin film of water surrounding soil particles for movement. Irrigation (1/4 inch) after a nematode application is thereby suggested to optimize soil conditions and to help move nematodes through the thatch. A light irrigation before the application will also reduce the chances of nematodes sticking to grass blades on the surface. Users are advised to check viability by examining nematodes for movement with a hand lens before application and again in a sample collected from the sprayer output.
Fungal entomopathogens. Beauveria bassiana (the “white muscardine” fungus) is a common soil-borne fungus that has been selected for its virulence to certain insect pests. When spores (conidia) attach to the insect cuticle, they germinate, penetrate with the growing hyphae, and proliferate within the insect’s body. Moist conditions favor germination, followed by infection of the insect host 1-2 days later, and ultimately death. The white appearance of the cadaver’s surface is due to the conidia produced by the mature reproductive structures of the fungus as they reemerge from the host. These infected cadavers serve as inocula for secondary spread of the pathogen in the environment.
The commercial product of Beauveria bassiana is produced through fermentation. Conidia are harvested and formulated into a sprayable liquid. Speed and efficacy of the product will depend on the number of spores contacting the insect, the age and susceptibility of the grub and the environmental conditions. Therefore, younger white grubs should be targeted because they are more susceptible than third instars. Additionally, after application, the area should be kept wet to promote germination and subsequent infection.
Milky spore disease. Milky spore disease powder is produced by grinding up living, diseased Japanese beetle grubs infected with the bacteria Paenibacillus popilliae. Commercial preparations of milky spore powder are widely used for the biological control of Japanese beetle. Nevertheless, the efficacy of current formulations has not been scientifically substantiated in the field, leading to questions about the usefulness of this biological control agent for white grub management. Users must also be aware that the bacteria in formulated products have been selected for infectivity to Japanese beetle grubs and are of no value against other common grub species infesting turfgrass in NY. This host specificity is highlighted on the product label. While Asiatic garden beetle, European chafer and Oriental beetle harbor the bacteria in natural populations, the commercial variety is specific to Japanese beetle.
While scouting, you may find milky grubs that are naturally infected with local strains of bacteria. The widespread occurrence of this pathogen under natural conditions means it does have prospects for biological control of white grubs. But, this will depend on further research and development to transfer laboratory virulence into field efficacy, as well as selecting more virulent bacteria that act against more species of scarabs under broad climate conditions. Practitioners seeking alternatives to chemical insecticides can try this product, but should not rely upon it.
More information online:
White grub control:
Japanese beetles:
Masked chafers:
Biological control:
Weevils
Description. The bluegrass billbug (BGB, Sphenophorus parvulus) and the annual bluegrass weevil (ABW, Listronotus maculicollis) are native weevil species. BGB is most injurious in high-cut, lower maintenance turf such as home lawns, athletic fields and golf course roughs. It impacts turf throughout the northern U.S. ABW is most injurious in low-cut, high maintenance turf such as golf course greens, tees and fairways. Until approximately 20 years ago, outbreaks were largely limited to southeastern NY, but now the area of impact has expanded throughout much of the state, north to New England and Quebec, west to Ohio, and south to Virginia.
Natural history. For BGB and ABW, females chew holes into the grass stem and insert eggs. Young larvae live as stem borers, chewing and consuming tissue within the relative protection of the stem and filling it up with frass (insect excrement) that looks like sawdust. When they outgrow the stem, older larvae will drop down to the soil surface where they forage out to chew on surface roots and crowns. Adults feed on grass blades but cause little damage. Both species develop through five larval instars, prepupa, pupa and adult. Pupation takes place in the top layer of the soil. BGB completes only one generation a year, while ABW completes two to three, and as many as four in southeastern NY.
Adults of both species are capable walkers, and largely disperse on foot even though they are capable of flight. In autumn, they mobilize to overwintering sites away from developmental areas. BGB adults, for instance, may settle into where sidewalks meet the lawn. ABW will seek out the relative protection of tree litter and tall grass, and may be most prevalent along defined tree lines or hedgerows bordering fairways.
Diagnosis. Adults have long snouts that are the hallmark of the weevils. BGB adults measure about 1/4-inch-long, or about twice the size of ABW (about 3/16 inch long). In addition to overall size, BGB adults can be differentiated from ABW because their antennae arise from the base of the snout, rather than the tip. Newly emerged adults, known as “callows” or “tenerals,” are chestnut to brown in color, making the young adults distinguishable from mature adults that are dark grey to black.
The bodies of BGB and ABW larvae are straight to slightly curved and creamy white in color with a well-defined brown head capsule. Unlike most beetles, weevil larvae are legless, meaning that they are easily distinguished from white grubs, which have six legs and a “C”-shape.
Injury caused by the stem boring and tunneling activities of younger larvae can be revealed through the “tug-test.” Brittle or weakened stems are easily pulled up by hand. Unlike white-grub injury, the soil and root zone remain firm and not spongy. BGB-damaged turf appears wilted, as if drought stressed, but it will not respond to watering. Damage is ultimately expressed as growing brown patches, especially near drought-prone edges such as pavement where grass may be more susceptible to heat or water stress. To distinguish BGB from drought stress, look for the frass as small pockets of sawdust-like material in the thatch or inside grass stems. BGB is most prevalent and damaging in Kentucky bluegrass. Damage is most apparent from late June through August.
ABW injury is usually expressed as growing areas of yellow and brown spots first noticed around the collar and perimeter of greens, tees and fairways. Early ABW damage has anthracnose-like symptoms and is frequently confused with this pathogen. Damage will be most prevalent in annual bluegrass, the favored host. It is unknown whether ABW can actually complete its life cycle on other hosts, even though it is capable of feeding on creeping bentgrass and perennial ryegrass. High populations of ABW will cause substantial areas of dead turf in highly visible and prominent areas of golf course playing surfaces.
BGB – Decision-making. BGB adults are most active in spring, from mid-May to June. It is common to see them strolling across pavement or sidewalks in the mid to late afternoon. One way to monitor them at this time of year is with pitfall traps. Make a hole with a standard golf course cup cutter, insert a plastic cup that fills the hole and is submerged to the rim, and add an inch of water with some dish detergent. If 7-10 billbugs fall in over a 2-3 week period, injury can be expected in the surrounding turf. Another approach in spring is to observe adults walking on paved surfaces adjacent to turf. Injury can be expected if >2 are observed per minute. For the larvae, tolerance thresholds are 8-12 per sq. ft.
BGB – Intervention. If potentially damaging populations are detected, chemical control applications should be made between mid-May and late June. This window targets adults once they have emerged from overwintering sites and before they lay eggs. It is best to mow before the application and irrigate lightly afterwards. This intervention should prevent severe damage by larvae in July and August.
In areas with persistent problems, host plant selection should be considered. One of the most susceptible cool season grasses is Kentucky bluegrass. This species should be avoided in favor of more tolerant alternatives. Endophytic cultivars of tall fescue and perennial ryegrass are also good options because they reduce BGB survival.
ABW – Decision-making. ABW can be challenging to monitor due to its small size. In the spring, mower baskets can be monitored for adults because they are picked up along with clippings. This can be a useful way to stay abreast of when adults are appearing in spring, and, with more careful monitoring, on which areas of the course they are most prevalent. Some areas of the course may always harbor ABW so it is a good idea to monitor consistently those historically affected areas from year to year. Adult ABW reinvade short-mown turf soon after snow melt and soil thaw, from late March to April.
A more site-specific approach to monitor adults is to pour a soapy disclosing solution on the turf. The standard method is to mix 1 fluid ounce lemon-scented dish detergent in 2 gallons water and apply it over 2-3 square feet of turf. The soap acts as an irritant, forcing adults to emerge from the thatch and ascend to the surface where they can be counted. Shallow soil core sampling or simply digging around at the soil surface/thatch interface will reveal older larvae and pupae. Older larvae look like grains of rice with brown heads; pupae resemble adults but are creamy white until their color darkens before adult emergence. If more detailed information is desired, larvae of all sizes (even stem boring stages) will float to the surface when an infested core is submerged and agitated in a saturated salt solution. This is a good way to confirm that your adult controls were adequate; if too many larvae are found, the application may have been poorly timed to suppress adults and another application against adults of the developing population may be necessary.
Damage thresholds are 30-80 larvae/sq. ft. for the spring generation. Given summer heat stress, thresholds drop to 10-40 larvae/sq. ft. for the summer generation. Nevertheless, field experience indicates that action may have to be taken at thresholds as low as 5-10 larvae/sq. ft. in order to avoid injury and minimize the threat of the subsequent generation.
ABW – Intervention. Best control is achieved by targeting early spring adult populations that represent overwintered insects returning to the short mowed turf. A preventive insecticide application is then made to suppress adult populations before eggs are laid. The timing of spring applications can be based on a plant phenological indicator. The most widely used is the period that occurs between Forsythia full bloom and flowering dogwood full bract. It is better to make the spring application a little late than a little early, so aim for the time when Forsythia is in full bloom and has already acquired many new leaves (i.e., “half gold/half green”).
Choose a relatively insoluble insecticide that stays in the thatch where adults are active. Chlorpyrifos and pyrethroids are the best options. Water in the application lightly, enough to move the material off the leaves. Widespread fairway applications are usually not necessary. It should be sufficient to limit applications to periphery sprays along historically susceptible greens, collars, tees and fairway perimeters. If this control fails, second generation adults can be targeted again sometime around July 4.
In southeastern NY, insect resistance to pyrethroid insecticides is well documented. It is unclear how widespread this resistance may be across the rest of the state. If you have made multiple seasonal applications of pyrethroid insecticides to target adults over several years, then your local populations may no longer be suppressed by these insecticides. Non-pyrethroid alternatives include chlorantraniliprole, cyantraniliprole, indoxacarb, spinosad and trichlorfon, which largely target larvae. Unlike the other larvicides, chlorantraniliprole should be applied early when overwintered adults reappear so it is fully activated once the larvae emerge. Given the difficulties in timing applications against ABW, all intervention approaches should be backed up by a sampling plan that will verify product efficacy. No insecticidal products have activity against the pupae.
With respect to cultural control, minimizing stress (e.g., due to water deficit or traffic) on annual bluegrass might mitigate the effects of ABW. Other than that, reducing the amount of annual bluegrass is the only other option as this may leave turf less favorable for the development of outbreak populations. Overwintering adults are sometimes very abundant in white pine litter, leading some golf courses to remove pine litter or even remove stands of white pine trees. Tree removal is not recommended, however, because these sites are not actually preferred locations for overwintering. Weevils will overwinter elsewhere. We may ultimately be able to define control practices based on managing adults in their overwintering habitats or by intercepting them as they return to developmental sites, but these opportunities have not yet been advanced.
More information online:
Annual bluegrass weevil:
Billbug:
Caterpillars
Description. Three groups of caterpillars damage turf in NY: cutworms, sod webworms and armyworms. Cutworms and armyworms largely refer to diverging habits of these moth larvae. Cutworms are solitary and tend to chew through and sever the grass stem at ground level, and then move on to the next plant. In contrast, armyworms are gregarious feeders, and tend to move across the turf eating all edible material in their paths. While there are a few species that can be injurious in turfgrass of NY, the main species of concern are the black cutworm (BCW, Agrotis ipsilon) and the fall armyworm (FAW, Spodoptera frugiperda). FAW and BCW do not usually overwinter in NY because they are too cold intolerant. Migratory adults reinvade the state every spring from populations that overwinter in the southern U.S. Sod webworms on the other hand are a complex of species that do overwinter in NY.
It should also be noted that the “true” or “common” armyworm (Mythimna unipuncta) is a sporadic invader in New York. Outbreaks typically occur in some area of the state every 3-8 years, and result from moths blown in on weather fronts from the southern or midwestern US. The infestation of 2012 was the most severe and widespread on record in NY. Like FAW, true armyworms are not known to overwinter here.
Sod webworms. Sod webworms are only sporadic pests and the cases are actually few where the larvae become problematic, despite the large numbers of adults that may be seen. Adults have snout-like projections on their face (thereby their common name “snout moths”) and have their wings folded close to the body when at rest. They are buff-colored and 0.5-0.75 inches long. They hide during the day. When disturbed by mowing, however, or at dusk, they fly in a zigzag pattern and are easy to spot.
Larvae construct silk-lined burrows through the thatch layer and into soil, incorporating debris such as soil, sand and grass clippings in the tunnel walls. They emerge at night to forage outside the burrows. Larvae grow up to 1-inch-long, are brown to green in coloration with a series of darker spots. Foraging birds may indicate infestations. Habitat preferences are for sunny areas, and they can affect low to high maintenance turf (e.g., home lawns and golf course turf). Sob webworms overwinter as larvae.
Damage starts as small patches of yellowing or browning grass, or grass clipped off at ground level where grass is turning brown. Look for small piles of green frass. On low-mown turf, sod webworm damage can resemble disease, and will cause small depressed marks of brown grass that grow in size.
The highly visible adults often concern home owners, but their presence does not indicate a pest problem. Therefore, the lawn has to be monitored for the larvae. More often than not, damage attributed to sod webworm on residential lawns is actually just drought stress—another reason it is important to scout for larvae. Conduct scouting for larvae two weeks after adult flights, when caterpillars from the new generation will be present. Scout near brown patches by spreading the grass and looking into the thatch to find the frass. Another way is to flush them to the surface using a soapy disclosing solution (see 6.2.2).
If the number of larvae or amount of damage warrants control, use less soluble insecticides that will stay in the thatch, such as pyrethroids. Because larvae are most active at night, a product should be applied as late in the day as possible. It should be watered in lightly, just enough to wash it off the leaves and into the thatch. Spinosad and Bt are biopesticide alternatives to conventional chemical insecticides for sod webworm management.
Black cutworm – Natural history. While BCW is common in low maintenance turf, it is particularly damaging in golf course greens and tees. Each spring adult moths reinvade NY from the southern U.S. along with spring storm fronts. This species is apparently incapable of overwintering in areas where the soil freezes. BCW can complete 2-3 generations a year in NY. Adults feed on flowers at night and then locate sites in the turf where they attach eggs to the tips of grass blades. Small larvae move across and feed on the surface. Older larvae, however, fashion a protective burrow in the turf from which they foray to feed. These burrows lead into the soil and are about the size of a pencil hole.
Black cutworm – Diagnosis and decision-making. BCW adults are dark grey and mottled with black and brown. Larvae bear a pale stripe down the back, a greasy or oily appearance, and have a surface integument that is rough or pebbly. Mature larvae will get to be 1-2 inches long. Nocturnal feeding will scalp grass around the burrow’s entrance, leaving irregular depressions that resemble ball-marks or even dollar-spot. Low-mown bentgrass is particularly susceptible to damage. Like sod webworms, foraging birds may help to indicate the presence of larvae.
The first appearance of adults in NY can be monitored in spring using either black light or pheromone traps set out early in the season. Both traps have limitations. Pheromone traps are relatively inexpensive and simple to maintain, but catch only male moths. While black light traps capture both male and female moths (along with a wide range of other insects), they are expensive and labor intensive. Because storm-driven moths are deposited randomly, there is no guarantee that lack of captures means that no females are present, nor is there any way to equate capture numbers to infestation levels; thus the usefulness of these traps is limited. A positive capture means only that chances are good that females are present and that larvae may appear within a week.
Monitoring for larvae should begin one to two weeks after the initial moth trap catches. Use a soap drench (see section 6.2.2) over 3-4 areas of the green’s surface to detect their presence. On golf course putting greens, damage may not be noticed until the larvae are quite large or have reached the fourth instar. At this point, the disclosing solution can confirm the diagnosis of cutworm damage. Pest management strategies, however, should target detection and treatment of cutworms before this stage. Thresholds will vary widely from greens and tees to fairways. While the visible damage of only 3-4 large larvae on greens might require a control, turf maintained at a higher cutting height can tolerate much higher populations before thinning is apparent.
Black cutworm – Intervention. Cultural control takes advantage of the fact that BCW lays the majority of eggs on the terminal portion of leaf blades, regardless of mowing height. Most eggs can therefore be removed if the clippings are collected. These should be discarded at least 100 feet away from susceptible turf areas to prevent return migration of the newly hatched caterpillars. Larvae shun feeding on Kentucky bluegrass. A 30-foot buffer of this grass around a golf course putting green significantly reduces the incidence of cutworms since they are less likely to cross this barrier to settle on the greens. Another alternative is to mow greens early in the morning, between 2 and 4 a.m., when cutworms are actively feeding on the surface. Target these mowings for three consecutive nights during the development of early instars for each cutworm generation. Planting endophytically-enhanced varieties of perennial ryegrass and tall fescue in appropriate areas is also an effective way to avoid or reduce damage.
Spinosad is a biologically-derived, low EIQ product that is effective against cutworms. It works best against young caterpillars, and is relatively fast acting. Otherwise, a range of chemistries work well for the curative control of BCW. Early-season detection and treatment is desirable because younger (smaller) cutworms are more susceptible than older (larger) cutworms. Higher rates might be required for the control of large larvae and for control in high-mown turf. Regardless, after application, irrigation and mowing should be withheld for 12-24 hours so larvae can contact the treated foliage.
Besides spinosad, Bt-based biopesticides are an alternative to conventional chemical insecticides. Bt is a non-living form of the bacterium Bacillus thuringiensis that is sold and labeled for management of caterpillars, including black cutworm, sod webworm and armyworm. This microbial toxin will also be most effective when targeting the more susceptible smaller larvae. As with chemical treatments, mowing and irrigation should be withheld 12-24 hours.
In the area of biological control, entomopathogenic nematodes have a good chance of success in managing BCW. Use the nematode species Steinernema carpocapsae. As with the biopesticides, apply when caterpillars are small, and follow the recommendations described in the section under white grubs. Finally, keep in mind that a diverse array of naturally occurring enemies, such as parasitic wasps and flies, ground beetles and rove beetles help to suppress cutworm populations.
More information online:
Black cutworm:
Fall armyworm:
Sod webworm:
Chinch Bugs
Description. The hairy chinch bug (HCB, Blissus leucopterus hirtus) occurs throughout NY, west to Minnesota, south to Virginia and north to Ontario and southeast Canada. Home lawns are the most susceptible turf habitats. The insect is most prevalent in areas with thick thatch, well-drained sandy soils and full sunlight. In addition, HCB is recently and increasingly recognized as an occasional pest on golf courses where it has traditionally been of little concern to superintendents.
Natural history. HCB has piercing-sucking mouthparts that permit the nymphs and adults to extract sap from the crowns and stems. This causes injury that produces drought-like symptoms. Most of the cool season grasses are susceptible to feeding. Both life stages are active and agile in the thatch and on the soil surface. HCB tends to form aggregations and this leads to patches of localized damage.
Although adults are capable of flight, they largely disperse by walking. Adults will move to overwinter in protected sites with thatch or tall grass, in debris and around structures. When they re-emerge in the spring, egg laying is preceded by a nearly 2-week preoviposition period. Up to 170 eggs per female are laid in leaf sheaths and on the ground near the base of host plants. Nymphs require 4-6 weeks to develop through five instars. One generation per year is most common in upstate NY and two generations is probably most common downstate.
Diagnosis. HCB are small and relatively fast-moving insects. Adults are 3/16 inches long, with shiny white wings. Nymph coloration varies from red to orange to brown. When captured by hand, odoriferous defensive glands on the abdomen will emit a powerful and pungent fruity smell.
The habitats most susceptible to HCB damage are home lawns with full sun and sandy soil where grass is more susceptible to drought stress. Abundance of the insect and severity of its injury are also favored by thick thatch. July and August are the months when the insect is most active and when most damage is expressed. HCB feeding causes symptoms that resemble water stress and can be misdiagnosed as such. Unlike drought, however, lawns that are heavily damaged by HCB will not recover once wet conditions are restored. Affected grass will turn yellow and then reddish-brown. Injury may be more prominent on the edges of paved areas.
Searching the soil surface should reveal the nymphs and adults. The tiniest nymphs are bright orange/red, and the adults are quick, which makes them relatively easy to spot despite their small size. HCB can also be detected and monitored with a flotation cylinder. Choose a spot on the fringe of a patch of damaged grass. Pound an open-ended coffee can about2 inches into the soil, fill it with water, and look for the adults as they float to the surface. Add more water as required if it filters into the soil. A 5-10-minute observation should be sufficient. Alternatively, remove a soil/turf core with a cup cutter or shovel, and submerge the sample in a bucket or pan filled with water.
Decision-making. If an infestation of HCB is detected, make several observations with the flotation cylinder at the margin of the affected areas. More than 20 HCB per cylinder means that action should be taken to avoid loss of turf. Population estimates can also be made with direct visual counts. More than 10 individuals found in a 60-second search of 1 sq. ft. has been used as an action threshold, as has 20-30 per sq. ft. in a detailed search. Make these abundance estimates at several sites around the affected area, and over time to judge whether levels are increasing or decreasing.
Intervention. Studies have shown a great deal of variation in HCB susceptibility across different cool season grass species and varieties. Therefore, host plant selection is a form of cultural control that can be used. Heavily or consistently damaged lawns should be renovated with a more tolerant grass variety. Endophytic cultivars of tall
fescues and perennial ryegrasses are the best options as they are resistant to HCB. Reducing thatch buildup should also lessen the severity of infestations.
Beauveria bassiana is a naturally occurring entomopathogenic fungus that can suppress HCB populations. Irrigation in spring and early summer helps to favor this fungus and promote its activity in the natural regulation of HCB. There is also a commercial formulation of B. bassiana that may be useful as an alternative to conventional chemical insecticides.
The traditional window for insecticidal control is mid-summer when HCB is most active. The optimal time is after overwintered adults have stopped laying eggs and before the nymphs from their earliest eggs have matured to adults. An alternative might be to target overwintered adults in early spring before they lay eggs. Before any chemical treatment, turf should be watered with 15-20 gallons water per 1000 sq. ft. Granular materials should be watered in after application.
More information online:
- unl.edu/turfent/documnts/chinchbg.shtml
- omafra.gov.on.ca/english/crops/facts/08-019.htm
- ento.psu.edu/extension/factsheets/chinchBugs.htm
Ants
Description and Natural history. Mound-building ants are nuisance pests of golf courses in the Northeast U.S. The most troublesome and widespread species is probably Lasius neoniger. This small, brown ant typically builds mounds that are concentrated around the edges of sand-based greens. A single nest may have several entrances, each with a squat volcano-shaped pile of soil. The main nest is usually located in the surrounding native soil. Mounds pushing up from within sand-based greens are typically the supplemental garrisons made by foraging workers. Mounding activity begins in early spring, increases through early summer, and declines by late summer at which point winged reproductive adults emerge and mate. Fertilized females then locate sites to overwinter and establish new colonies the following spring.
Decision-making. Monitoring for mound-building ants should begin with mid-summer mapping of problem areas across the golf course or other turf habitat. Then, early in the following growing season, monitor for ant activity in the areas that had high mound pressure the previous season. This is where control measures will need to be focused. Beyond greens, if mapping shows that the ants are moving in from golf course roughs, treatments can be targeted at the rough/fairway interface.
Intervention. Insecticides should only be expected to suppress, not eliminate, ant populations. Killing the colony’s queen is difficult, and even if she dies, she can be replaced and the colony will persist. Ant colonies are most susceptible in the early season, when they are small and the queen is relatively weak from overwintering. When applied early, surface insecticides such as chlorpyrifos, can give 4-6 weeks suppression. Those applied later in season, however, may only offer 2-3 weeks suppression.
Insecticidal controls should focus on the perimeter of greens, collars, and roughs adjacent to main nests. This will best target the colony at the entrances to the main nest. An application made to the surface of the green itself will target the entrances of the auxiliary tunnels, but miss the main nest entrance that may be less visible in the higher-mown turf of the collar or rough.
There is mixed advice about using baits as part of a control program. The baits are granular products that contain insecticides and are broadcast applied on and around ant mounds in turf. They may be most effective when used after an initial knock-down application of a pyrethroid. However, the granule size of many baits may be too large and because these ants are generalists, the baits may not always attract them.
Exotic Crane Flies
Description. Invasive European crane fly pests of turfgrass were detected for the first time in NY in 2004. Since then they have emerged as tremendously injurious insects. The larvae are the damaging life stage, commonly referred to as “leatherjackets” (although this may actually refer to the exuvium left behind when the adult emerges from the pupa). Two species, Tipula paludosa (the “European crane fly”) and Tipula oleracea (the “common crane fly”), were originally detected in western NY. Both species are native to Europe but are now established in three geographic areas of North America: the Pacific Northwest (British Columbia, California, Oregon, Washington), eastern Canada (Newfoundland, Nova Scotia, Quebec), and the eastern Great Lakes (Massachusetts, Michigan, Ontario, New York). In NY, 2004 populations were only detected in Erie and Niagara counties. By 2010, T. paludosa had been detected in 11 counties (Chautauqua, Erie, Genesee, Monroe, Niagara, Oneida, Ontario, Orleans, Tompkins, Wayne, Wyoming), while T. oleracea had become more widespread, being detected in 18 counties (Broome, Cortland, Erie, Genesee, Livingston, Monroe, Nassau, Niagara, Oneida, Onondaga, Ontario, Orleans, Oswego, Seneca, Suffolk, Tompkins, Wayne, Wyoming). Based on these observations, there are probably two separate areas of establishment, the western Erie Canal corridor (both species) and Long Island (T. oleracea). Until we build awareness and establish safeguards to curtail range expansion, movement of infested materials could spread locally and regionally, across NY and into New England and the Mid-Atlantic.
Natural history. The majority of the crane fly lifecycle is spent in the damaging larval stage. The short-lived adults resemble oversized mosquitoes, but they do not feed and are non-damaging. Adults are 2.5-3.0 cm long, pupae 3.0-3.5 cm, mature larvae 3-4 cm and eggs 0.1 cm.
Tipula paludosa completes one generation a year, with the emergence of adults occurring over a period of 2-3 weeks at any one site in September and October. Adult females will emerge, mate and lay most of their eggs all within the first day of their brief reproductive lives, even though adults may persist for several days. Each female will deposit up to 200-300 black eggs at or near the soil surface; these eggs will hatch into larvae in about 10 days.
Larvae of T. paludosa develop through four instars before they pupate. Active larvae mostly inhabit the top 3 cm of the soil where they feed on root hairs, roots and crowns of grass host plants. Larger larvae will also emerge to forage on stems and grass blades on the soil surface. Larvae usually achieve third instar by the onset of winter. Most damage is attributed to the feeding of rapidly growing fourth instars in spring. By early to mid-June, larvae have achieved their maximum size and move 3-5 cm deep in the soil. They remain in a relatively non-feeding and inactive state until pupation, which ends when pupae wriggle to the surface so the adult fly can emerge. The empty pupal cases (exuviae, or the “jackets” of the leatherjackets) look like small grey-black twigs protruding from the turf where they can be spotted on low-mown grass such as golf course playing surfaces.
While the biology of T. oleracea is quite similar to T. paludosa, certain differences mean that management has to be tailored to the specific species. A major difference is that T. oleracea completes two generations a year, emerging in two peaks, one in spring (early May in western NY) and the other in autumn coinciding with T. paludosa. The larvae of T. oleracea never enter an inactive summer stage like T. paludosa. Larvae overwinter as fourth instars and pupation occurs in early spring. Adult T. oleracea differ from T. paludosa in being more capable fliers, with females laying eggs over the course of a few days.
Eggs of both species are sensitive to moisture and require wet conditions to hatch and survive. Larvae also do best under moist conditions, but once they are third and fourth instars they are quite tolerant of drought. Overall, mild winters and cool summers will probably favor crane fly populations. Other turf conditions such as thatch buildup, poor drainage and regular irrigation will likely favor crane fly survival and population buildup.
Diagnosis. There are hundreds of native crane fly species in NY and a few of them inhabit grassy habitats including turf. Native species are ostensibly non-damaging because none have been implicated in any turf injury in NY. Because of this, it is important to differentiate the injurious exotic species from the natives. The best physical character to separate them is based on wing pattern. Both exotic Tipula species have a narrow smoky band on the leading edge of the wing adjacent to a bordering whitish band. Unlike many native species, they have no other pigmentation on the wing. One widespread and locally abundant native species, however, is only differentiated because there is a break in the smoky band. Beyond that, characteristics of the male genitalia, ventral distance between the eyes, number of antennal segments, and length of the wing with respect to length of the abdomen permit the differentiation of exotic crane flies from native species, and also T. paludosa from T. oleracea. Nevertheless, species identification should be made or confirmed by a specialist.
Leatherjackets are serious pests of both low- and high- maintenance turf, from home lawns and golf courses to sod farms. Based on experience in the Pacific NW, pastures and grass seed fields can also be impacted. Spring densities of up to 70, 120 and 50 larvae/sq. ft. in highly damaged lawns, fairways and putting greens, respectively, have been recorded in the greater Buffalo and Rochester areas. Five categories of damage have been observed: nuisance populations of adult flies and larvae in suburban settings, thinning damage to home lawns, chewing damage to the surface of golf course putting greens, thinning and die-back on golf course fairways and rough, and vertebrate predation due to skunks and birds. In addition, it has been recently confirmed that larvae can survive harvest, transport and installation of sod. The movement of infested sod or other soil media will lead to new establishments and human-mediated range expansion.
Due to the relatively synchronous emergence of local adult populations, homeowners in suburban settings have experienced nuisance swarms of adults. Adults will settle on the sides of buildings, window screens and landscaping plants, and the public may mistake them for giant mosquitoes. In fact, the first reports of invasive crane flies for both Long Island and the Rochester area were made by homeowners. High larval densities may also act as nuisance populations as rain showers can wash them off sloped lawns and amass them as piles of maggots in culverts.
On affected home lawns and golf course fairways, root pruning leads to white grub-like damage. The disruption of the rooting zone promotes rapid die-off when the injured turf is drought-stressed. Another expression of injury is extreme thinning due to surface feeding. Early to mid-May is when injury is most likely to be expressed by T. paludosa because large larvae are feeding rapidly as they approach the end of development. On affected golf course putting greens, foliar feeding by larvae on crowns and leaf blades causes damage akin to black cutworms. Larvae will reside in aerification holes or in self-made burrows from which they emerge to forage, chewing shallow quarter-sized pits into the playing surface.
Monitoring. To detect the presence of invasive crane flies, the leathery pupal cases can be monitored on tees, greens and fairways where they protrude from the low-mown turf. At times of peak emergence, the adults are abundant and highly visible as they flit about low in the grass. Adults may also congregate during the day on the sides of buildings, sliding doors, window screens and fences. Because adults lay eggs so soon after emergence, they do not move far from the sites where larvae developed. Therefore, sites with abundant adults, larvae or pupal cases should be monitored as an indication of sites where eggs of the next generation are likely to be laid. If a crane fly infestation is suspected, send adults, larvae or pupal cases to a specialist for proper identification.
If signs of insect activity and turfgrass injury suggest leatherjackets, core sampling is the best way to detect and sample larvae. Larvae can be monitored in the late autumn or early spring. Take samples with a cup cutter and rip apart the core to look for larvae. Traditional soap-based disclosing solutions (see 6.2.2) are not effective at driving larvae to the surface. Certain insecticides such as pyrethroids and carbamates, however, will reveal the presence of larvae because many will move to the surface before dying, often within 1-12 hours. This approach is most effective when soil water content is high and insecticides can readily penetrate the soil surface.
Decision-making. Control tactics should be directed against the larvae because adults are hard to target and short-lived. Depending on the overall health of the turf, suggested thresholds are 15-50 larvae/sq. ft. Autumn populations are likely to surpass these thresholds, but it is important to keep in mind that leatherjackets can suffer very high mortality between late autumn and early spring due to winter stress and predation by birds and other vertebrates. Vigorous turf can therefore support relatively high population levels in autumn and visible damage is highly unlikely.
Intervention – Cultural control. Because of their relative sensitivity to dry conditions, careful manipulation of soil moisture levels may be a key cultural tactic to reduce populations. Some strategies might be to regulate the timing and frequency of irrigation, particularly during the oviposition period, to better drain chronically infested areas and to allow the sward to dry (i.e., avoiding irrigation) in autumn. Maintaining a vigorous stand that is more tolerant to infestation might also alleviate problems.
Intervention – Chemical control. The two main control windows are late autumn and early spring. Since adults of both species emerge during a similar window in September, small larvae of both species would be susceptible to preventive insecticides. Therefore, a late autumn preventive application is recommended if populations of both species occur at the same site. Timing should be after peak emergence of adults in order to overlap the period of egg hatch and first instars.
Otherwise, curative applications for T. paludosa can be made in early spring after scouting reveals populations or once feeding damage is detected. Tipula oleracea is probably not susceptible during this window because it pupates early in spring and insecticides are not active against pupae.
The aforementioned control windows, unfortunately, do not coincide with other turfgrass pests. The arrival and spread of these exotics thereby represents a worrisome new economic burden for turfgrass managers. To identify the best chemistries for invasive crane fly control in NY, a series of field efficacy trials has been conducted against T. paludosa. Based on consistency and efficacy, a series of chemistries is acceptable for preventive late autumn control, including bifenthrin, carbaryl, chlorantraniliprole, imidacloprid, indoxacarb and trichlorfon. Among the best products for curative spring control are carbaryl, chlorpyrifos, imidacloprid and trichlorfon. Overall, insecticidal efficacy declines from autumn to spring as the larvae grow larger.
Intervention – Biological control. In addition to registered chemical insecticides, a registered biological control option is Beauveria bassiana, an entomopathogenic fungus. The entomopathogenic nematode, Steinernema carpocapsae, is another biological alternative that has been promoted in the Northwest.
More information online:
Northeast:
Pacific Northwest: