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Extension Entomology

Category: Lawn and Garden

Mimosa Webworm

–by Dr. Raymond Cloyd

Mimosa webworm (Homadaula anisocentra) larvae (=caterpillars) are now feeding and creating protective habitats on honeylocust (Gleditsia triacanthos) and mimosa (Albizia julibrissin) trees, which are quite noticeable in the Manhattan (KS) area. The larvae (=caterpillars) are 1/2 inch long when fully-grown (Figure 1),

Fig 1. Mimosa Webworm Caterpillars Feeding On Leaves (Auth–Raymond Cloyd, KSU)

Fig 2. Mimosa Webworm Webbing On Branch End (Auth–Raymond Cloyd, KSU)

Webbing commonly starts at the tops of trees and serves to protect caterpillars from natural enemies (parasitoids and predators) and insecticide spray applications. Heavily-infested trees are brown or scorched in appearance (Figure 3) as the caterpillars skeletonize the leaf tissue. Caterpillars eventually fall from trees on a silken strand before pupating. Mimosa webworm pupates in bark crevices or pupae are glued to structures (e.g. buildings).

Fig 3. Mimosa Webworm Feeding Damage (Auth–Raymond Cloyd, KSU)

In regards to controlling mimosa webworm infestations, it is probably too late although initial damage may be minimal. Insecticides that can be used to suppress mimosa webworm populations, in which the caterpillars are exposed, include: acephate (Orthene), Bacillus thuringiensis subsp. kurstaki (Dipel), spinosad (Conserve), and several pyrethroid-based insecticides (e.g. bifenthrin, cyfluthrin, and permethrin). Read the label of each product to ensure that “webworms” are listed. High-volume spray applications are required to contact the caterpillars inside the protective webbing. If trees are already heavily-infested with webbing then it is too late to apply an insecticide. If possible, selective pruning can quickly remove isolated or localized infestations of mimosa webworm.

Green June Beetle Adults

–by Dr. Raymond Cloyd

Green June beetle, Cotinis nitida, adults are actively flying around in massive numbers near managed and/or unmanaged grassy areas, and ‘bumping’ into people and objects. Adults are 3/4 to 1.0 inch long, velvety-green, and tinged with yellow-brown coloration (Figure 1). Green stripes with yellow-orange margins extend lengthwise on the front wings. The underside of the body is distinctly shiny and metallic green or gold. Adults resemble ‘dive bombers’ flying around for several weeks in July. Green June beetle adults are sometimes confused with Japanese beetle (Popilla japonica) adults—but they really do not look alike (Figures 2 and 3).

Fig 1. Green June Beetle Adult (Auth–Raymond Cloyd, KSU)

Fig 2. Green June Beetle Adult (Auth–Raymond Cloyd, KSU)

Fig 3. Japanese Beetle Adult (Auth–Raymond Cloyd, KSU)

Green June beetle has a one-year life cycle, and overwinters as a mature larva or grub. Adults generally emerge in late-June and are active during the day, resting at night on plants, in thatch, or in compost. Adults produce a sound similar to that of bumble bees. Adults will feed on ripening fruits and corn tassels, and may occasionally feed on plant leaves. Male beetles swarm in the morning, ‘dive bombing’ to-and-fro just above managed and/or unmanaged grassy areas where females are located. Females emit a pheromone that attracts the males. Clusters of beetles may be seen on the surface of the soil or in grassy areas with several males attempting to mate with a single female, resulting in an ‘insect orgy.’

Mated females that survive the ‘experience’ will lay clusters of 10 to 30 eggs in moist soil containing a high amount of organic matter. Eggs hatch in about two weeks, in early August, and young larvae feed near the soil surface. The larvae feed primarily on organic matter including thatch and grass-clippings; preferring material with a high moisture content. Larvae are 3/8 (early instars) to 1.5 (later instars) inches long, and exhibit a strange behavioral trait—they crawl on their back—likely due having a constant itch.

 

 

New Extension Publication

–by Dr. Raymond Cloyd

We have a new extension publication available entitled, Scale Insect Pests

 

This new extension publication provides information on the biology, scale types, plant damage, and offers strategies for managing specific types of scales. There are color images of the scale insect pests found in Kansas and surrounding states. The extension publication is available from the following website:

https://www.bookstore.ksre.ksu.edu/pubs/MF3457.pdf

 

Japanese Beetles

— by Dr. Raymond Cloyd

Japanese beetle, Popilla japonica, adults are present in most regions of Kansas feeding on different plant species, including: roses, Rosa spp.; littleleaf linden, Tilia cordata; and Virginia creeper, Parthenocissus quinquefolia, among many other plant species. The ways to manage populations of the adult stage of Japanese beetle are limited, and have been for many years, with the use of insecticides still being the primary strategy. Japanese beetle adults are one of the most destructive insect pests of horticultural plants in landscapes and gardens. Furthermore, the larva or grub is a turfgrass insect pest in home lawns, commercial settings, and golf courses.

 

Japanese beetle adults are 9/16 of an inch long, metallic green with coppery-brown wing covers, and about 14 tufts of white hair are present along the edge of the abdomen (Figure 1).

Fig 1. Japanese Beetle Adults Feeding On Leaf (Auth–Raymond Cloyd, KSU)

Adult Japanese beetles emerge from the soil and live up to 45 days feeding on plants over a four-to-six-week period. Adults feed on many horticultural plants including: trees, shrubs, vines, herbaceous annual and perennials, vegetables, fruits, and of course—roses. Plant placement in the landscape and the volatiles emitted by plants are factors that affect adult acceptance. In addition, Japanese beetle adults produce aggregation pheromones that attract males and females to the same feeding location. Adults can fly up to five miles to locate a host plant; however, they tend to only fly short distances to feed and for females to lay eggs.

Japanese beetle adults feed through the upper leaf surface (epidermis) and leaf center (mesophyll), leaving the lower epidermis intact. Adults avoid feeding on tissue between leaf veins, resulting in leaves appearing lace-like or skeletonized (Figure 2).

Fig 2 Japanese Beetle Adult Feeding Damage On Leaf (Auth–Raymond Cloyd, KSU)

They are most active during warm days, feeding on plants exposed to full sun throughout the day, which is likely why roses are a susceptible host plant because roses require at least six hours of direct sunlight to flower. Japanese beetle adults start feeding at the top of plants, migrating downward after depleting food sources. Japanese beetle adults will also feed on flowers (Figure 3),

Fig 3. Japanese Beetle Adults Feeding On Rose Flower (Auth–Raymond Cloyd, KSU)

chewing holes in flower buds, which prevents flowers from opening or causes petals to fall prematurely.

Managing Japanese beetle adult populations involves implementing a variety of plant protection strategies, including: cultural, physical, and applying insecticides. Cultural control is affiliated with maintaining healthy plants through proper irrigation, fertility, mulching, and pruning, which are important in minimizing ‘stress’, and may possibly decrease susceptibility. Moreover, removing weeds that are attractive to Japanese beetle adults such as smartweed (Polygonum spp.) may help to reduce infestations. Physical control involves hand-picking or collecting Japanese beetle adults from plants before populations are extensive. The best time to hand-pick or collect adults is in the morning when ambient air temperatures are typically ‘cooler.’ Adults can be easily collected by placing a wide-mouthed jar or bucket containing rubbing alcohol (70% isopropyl alcohol) or soapy water underneath each adult, and then touching them. Adults that are disturbed fold their legs perpendicular to the body, and fall into the liquid and are subsequently killed. This procedure, when conducted daily or every-other-day, for at least three weeks, particularly after adults emerge, may substantially reduce plant damage. A study reported that collecting Japanese beetle adults daily at 7:00 pm had the greatest impact on populations and reduced subsequent damage.

 

In general, the use of Japanese beetle traps (Figure 4) in a landscape or garden is not recommended since the floral lure and synthetically-derived sex pheromone may attract more adults into an area than would ‘normally’ occur. Japanese beetle adults may also feed on plants before reaching the traps, which increases potential damage.

 

Spray applications of contact insecticides will kill Japanese beetle adults. However, repeat applications are required; especially when populations are excessive. Several pyrethroid-based insecticides; such as those containing permethrin (Sevin®), bifenthrin or cyfluthrin as the active ingredient, will suppress Japanese beetle adult populations. However, most of these insecticides will also directly harm many natural enemies (parasitoids and predators) and continual use will result in secondary pest outbreaks of other pests including the twospotted spider mite, Tetranychus urticae. In addition, these insecticides are directly harmful to honey bees and bumble bees. Therefore, applications should be conducted in the early morning or late evening when bees are less active. In general, systemic insecticides are not effective against Japanese beetle adults because they have to feed on leaves and consume lethal concentrations of the active ingredient. If extensive populations are present, plant damage can still occur.

 

PHOTO NOT AVAILABLE

The battle against Japanese beetle adults requires diligence, patience, and persistence, to prevent adults from causing substantial damage to plants in landscapes and gardens.

 

 

Mosquitoes: How to Avoid Being “Bitten” by This “Sucking” Insect

–by Dr. Raymond Cloyd

The current wet weather and standing water has provided “perfect” conditions for mosquitoes (Figures 1 and 2). The three primary strategies that must be implemented to avoid mosquito problems and bites are: 1) source reduction, 2) personnel protection, and 3) insecticides.

Fig 1. Mosquito Sucking Blood (Author–Inverse

Fig 2. Mosquito Magnet Sign (Auth–Raymond Cloyd, KSU)

1) Source Reduction
It is important to routinely eliminate or reduce all mosquito breeding sites, which will effectively decrease mosquito populations, by removing stagnant or standing water from items or areas that may collect water. These include the following:
* Wheelbarrows
* Pet food or water dishes
* Saucers/dishes underneath flower pots
* Empty buckets
* Tires
* Toys
* Wading pools
* Birdbaths
* Ditches
* Equipment
* In addition, check gutters regularly to ensure they are draining properly and are not
collecting water

2) Personnel Protection
Protect yourself from mosquito bites by delaying or avoiding being outdoors during dawn or dusk when most mosquitoes are active. Use repellents that contain the following active ingredients: DEET (Figures 3 and 4) or picaridin (Figure 5). Generally, DEET provides up to 10 hours of protection whereas picaridin provides up to 8 hours of protection. A product with a higher percentage of active ingredient will result in longer residual activity or repellency. For children, do not use any more than 30% active ingredient. Furthermore, do not use any repellents on infants less than two months old. Clothing can be sprayed with DEET or permethrin (pyrethroid insecticide). However, be sure to wash clothing separately afterward. Before applying any repellent, always read the label carefully.

Fig 3. DEET Repellents (Auth–Raymond Cloyd, KSU)

Fig 4. DEET Repellent (Auth–Raymond Cloyd, KSU)

Fig 5. Repellent With Picaridin (Auth–Raymond Cloyd, KSU)

3) Insecticides

For stationary ponds, there are several products that may be used, such as; Mosquito Dunks and/or Mosquito Bits (Figure 6). Both contain the active ingredient, Bacillus thuringiensis subsp. israelensis, which is a bacterium ingested by mosquito larvae that results in death. The bacterium only kills mosquito larvae with no direct effects to fish or other vertebrates. Avoid making area-wide applications of contact insecticides because these are generally not effective, and may potentially kill many more beneficial insects and pollinators (e.g. bees) than mosquitoes.

Fig 6. Mosquito Dunks and Mosquito Bits (Auth–Raymond Cloyd, KSU)

What Does Not Work Against Mosquitoes 

The following items will not control mosquitoes:

* Mosquito repellent plants (citronella plants)

* Bug zappers

* Electronic emitters

* Light traps/carbon dioxide traps.

If anyone has questions or comments regarding mosquito control please contact your county extension office or Department of Entomology at Kansas State University (Manhattan, KS).

Fall Webworm

–by Dr. Raymond Cloyd

The first generation of fall webworm (Hyphantria cunea) is now prevalent in most of Kansas with webs present on certain trees. Fall webworm nests are very noticeable, with silk webbing enclosing the ends of branches and foliage or leaves (Figures 1 and 2).

Fig 1. Fall webworm nest on walnut tree (Auth–Raymond Cloyd, KSU

Fig 2. Fall webworm nest on birch tree (Auth–Raymond Cloyd, KSU

Fall webworm larvae or caterpillars are pale-green, yellow to nearly white, with two black spots on each abdominal segment. Caterpillars are covered with long, white hairs (Figure 3).

Fig 3. Close-up of fall webworm larvae (Auth–Raymond Cloyd, KSU)

 

Fall webworm caterpillars feed on a wide range of trees, including: birch, crabapple, maples, hickory, pecan, mulberry, and walnut. Fall webworm caterpillars, unlike eastern tent caterpillars, remain within the enclosed webbing and do not venture out to feed. Caterpillars consume leaves, resulting in naked branches with webbing attached that contains fecal deposits or ‘caterpillar poop.’ These nests will eventually dry-up as the caterpillars pupate, with adults’ eclosing (emerging) from pupae later on.

 

Feeding by fall webworm caterpillars may ruin the aesthetic appeal of infested trees; however, the damage is typically not directly harmful to trees—especially larger trees. The most effective method of dealing with fall webworm infestations is to simply prune-out the webs that enclose the caterpillars, place into a plastic bag, and dispose of immediately. Insecticide sprays may not be effective because the caterpillars remain in the webbing while feeding; thus reducing exposure to spray residues. If insecticides are used, be sure to use high-volume spray applications that penetrate the protective webbing, or use a rake to disrupt or open-up the webbing so that the insecticide spray contacts the caterpillars.

 

 

Time To ‘Get Ready’ For Bagworms

–by Dr. Raymond Cloyd

For those of you that have been waiting patiently or for some…impatiently; it is time to ‘get ready’ to spray for bagworms. In due time, bagworms will be present throughout Kansas feeding on broadleaf and evergreen trees and shrubs. Therefore, now is the time to initiate action against bagworms once they are observed on plants. Bagworms are primarily a pest of conifers; however, they have expanded their host range to include a number of broadleaf plants, such as; rose, honey locust, and flowering plum. It is important to apply insecticides when bagworms are small to maximize effectiveness and subsequently reduce plant damage.

A number of insecticides are labeled for use against bagworms including those with the following active ingredients (common trade names are in parentheses): acephate (Orthene), Bacillus thuringiensis subsp. kurstaki (Dipel), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), trichlorfon (Dylox), indoxacarb (Provaunt), chlorantraniliprole (Acelepryn), and spinosad (Conserve). Most of these active ingredients are commercially available and sold under various trade names or as generic products. Several insecticides, however, may not be directly available to homeowners.

The key to managing bagworms with insecticides is to apply early and frequently enough to kill the highly susceptible young caterpillars feeding on plant foliage (Figure 1).

Figure 1. Young bagworm larvae or caterpillar feeding on conifer (Author–Raymond Cloyd, KSU)

Older caterpillars that develop later in the season are typically more difficult to kill with insecticides. Moreover, females feed less as they prepare for reproduction, which reduces their susceptibility to spray applications and any residues. The bacterium, Bacillus thuringiensis subsp. kurstaki, which is sold under various trade names (Figure 2

Figure 2. Product (Thuricide) containing Bacillus thuringiensis subsp. kurstaki as the active ingredient (Author–Raymond Cloyd, KS)

), is only active on young caterpillars and must be consumed or ingested to be effective. Therefore, thorough coverage of all plant parts and frequent applications are required. The insecticide is sensitive to ultra-violet light degradation and rainfall, which can reduce residual activity (persistence). Spinosad is the active ingredient in a number of homeowner products, including: Borer, Bagworm, Tent Caterpillar, and Leafminer Spray; Captain Jack’s DeadBug Brew (Figure 3);

Figure 3. Product containing spinosad as the active ingredient (Author–Raymond Cloyd, KSU)

and Monterey Garden Insect Spray. The insecticide works by contact and ingestion; however, activity is greatest when ingested by bagworms. Last year (2018), I made weekly applications for four-weeks in June and killed nearly 100% of the bagworms on my arborvitae and juniper shrubs. Consequently, the plants looked aesthetically pleasing during the season.

Cyfluthrin, lambda-cyhalothrin, trichlorfon, chlorantraniliprole, and indoxacarb can be used against where bagworms commonly start feeding, and frequent applications are essential in achieving sufficient suppression of bagworm populations. The reason multiple applications are needed is that bagworm eggs do not hatch simultaneously but hatch over a certain period of time depending on temperature, and young bagworms can ‘blow in’ (called ‘ballooning’) from neighboring plants on silken threads. If left unchecked, bagworms can cause significant damage and ruin the aesthetic quality of plants. In addition, bagworms can actually kill plants, especially newly transplanted small evergreens, since evergreens do not usually produce another flush of growth after being fed upon or defoliated by bagworms

If you have any questions on how to deal with bagworms in your garden or landscape contact your county horticultural agent, or university-based or state extension entomologist.

 

 

Ticks

— by Dr. Jeff Whitworth and Dr. Holly Davis

 

Ticks are becoming more active this spring, especially wood ticks, also called American dog ticks, Dermacentor variabilis.  These are probably the most common tick encountered in Kansas and they are more common in grasses around field borders and areas with more trees.  They can transmit several diseases and thus should be carefully and safely removed, head intact, before feeding occurs for more than a few minutes, if possible.  For more information on the species of ticks found in Kansas, please see Household Pests of Kansas (pg. 97): https://www.bookstore.ksre.ksu.edu/pubs/MF3291.pdf

 

Grasshoppers

— by Dr. Jeff Whitworth and Dr. Holly Davis

Just started finding very small, recently hatched grasshopper nymphs.  If, or when, these nymphs start to increase in numbers in the next few weeks, remember the best time to manage them is while they are still small and thus, less mobile.  An application of an insecticide labeled for grasshopper control is most effective, cheaper, and less environmentally disruptive if applied early so it can be better targeted in a smaller area at the most susceptible time to control these pests.

Termites

— by Dr. Jeff Whitworth and Dr. Holly Davis

The last few days of warm, sunny conditions after the preceding few days of cooler, wet weather have apparently initiated considerable termite swarming activity.

Again, make sure to positively identify the insects swarming, as ants are also actively swarming.  There is a huge difference in damage potential between termites and ants, even carpenter ants.  So, please refer to these KSU extension publications to properly identify and manage ants and termites:

 

Termites, MF722: https://www.bookstore.ksre.ksu.edu/pubs/MF722.pdf

Ants, MF2887: https://www.bookstore.ksre.ksu.edu/pubs/MF2887.pdf

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