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Extension Entomology

Category: Horticulture

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.

 

 

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

How to Avoid Getting “Bored” by the Ash/Lilac Borer

–by Raymond Cloyd

 

Now is the time to take “action” to prevent damage from the ash/lilac borer (Podosesia syringae). Ash/lilac borer adults are typically active from late-April through June, although activity is contingent on temperature. Adults are brown, clearwing moths that look-like paper wasps (Figure 1). Adult females lay tan, oval-shaped eggs in cracks and crevices, or wounds at the base of plant stems. One female can live for approximately one week and lay up to 400 eggs. Below are nine points associated with the life history and management of ash/lilac borer:

 

Fig 1. AshLilac Borer Adult (Author–City of Edmonton)

  1. The larvae are responsible for causing plant damage by tunneling and feeding within the bark (cambium). Larvae can also tunnel further into the wood and feed within the sapwood and heartwood.
  2. Larval feeding restricts the flow of water and nutrients; thus resulting in shoot or branch dieback. Ash/lilac borer larvae feed at the base of plant stems causing swollen areas or cracks, and they also feed where major branches attach to the trunk.

 

  1. The presence of light-colored sawdust (frass) accumulating at the base of infected trees or shrubs (Figure 2) is evidence of larval feeding.

Fig 2. Sawdust Located At The Base Of An Infected Tree (Auth–Raymond Cloyd, KS)

  1. Ash/lilac borer overwinters as a late-instar larva located in feeding tunnels or galleries.

5. Trees or shrubs infested with ash/lilac borers will have brown papery pupal cases protruding from the bark (Figure 3), which is where adults emerge from.

Fig 3. Pupal Cases of AshLilac Borer Protruding From Tree Trunk (Auth–Raymond Cloyd, KSU)

 

  1. There is generally one generation per year in Kansas.

 

  1. The primary means of avoiding problems with ash/lilac borer is to avoid ‘plant stress’ by providing proper cultural practices including; irrigation (watering), fertilization, pruning, and mulching. In general, stressed plants are more susceptible to attack by ash/lilac borer than ‘healthy plants.’ A two to three foot wide mulched area around the base of trees and shrubs prevents injury from lawn mowers and weed-trimmers that can girdle trees and shrubs leading to ‘stress.’ Moreover, avoid pruning plants in late spring through early summer (under usual weather conditions) as this is when adults are typically present and the volatiles emitted from pruning cuts may attract adult females.

 

  1. Insecticides containing the active ingredients, permethrin, bifenthrin, or chlorantraniliprole can be applied to the bark—at least up to six feet from the base—to prevent ash/lilac borer larvae from entering which exposes them to insecticide sprays. Once larvae are inside the plant, they are not susceptible to insecticide sprays. Systemic insecticides applied to the soil or injected into trees or shrubs do not provide reliable control of the ash/lilac borer.

 

  1. Commercially available pheromone traps capture adult males, which help estimate when females will be laying eggs. Pheromone traps help appropriately time insecticide applications. Insecticide spray applications should begin seven to 10 days after capturing the first adults. Check pheromone traps two to three times per week for the presence of newly captured adult males.

 

Common Asparagus Beetle

–by Dr. Raymond Cloyd

If you are growing asparagus then it is that time of year to be aware of the only insect pest of asparagus; the common asparagus beetle, Crioceris asparagi. Adult beetles are 1/4 inch long. The body is metallic blue to black with red margins and six cream-colored markings (Figure 1).

Figure1. Common Asparagus Beetle Adult (Author–Raymond Cloyd, KSU)

Adults emerge from the soil in early spring and fly to new asparagus shoots where they mate and feed. Females lay up to 30 eggs on the end of spear tips as they emerge from the soil (Figure 2)

Figure2. Common Asparagus Beetle Eggs on Spear Tip of Asparagus (Author–Raymond Cloyd, KSU)

Larvae hatch from eggs after about a week, migrate onto the ferns, and commence feeding. The larvae look like a small slug. They are wrinkled, 1/3 inch in length, and olive-green to gray with black heads and legs (Figure 3).

 

Figure3. Common Asparagus Beetle Larvae Feeding on Asparagus (Author–Raymond Cloyd, KSU)

Larvae feed for approximately two-weeks and then drop to the ground, burrow into the soil, and form a yellow pupa. After several weeks, adults emerge and start feeding. Common asparagus beetles overwinter underneath plant debris, loose bark, or hollow stems of old asparagus plants. The life cycle can be completed in eight-weeks. There are two generations in Kansas.

The adults and larvae feed on asparagus spears and can defoliate ferns if populations are extensive. Larvae consume leaves and tender buds near the tips, which leaves scars that eventually turn brown. Damage caused by larvae interferes with the plant’s ability to photosynthesize (manufacture food); thus depleting food reserves for next year’s crop.

The plant protection strategies that can be implemented to reduce problems with common asparagus beetle populations include: applying insecticides; hand-picking eggs, adults, and larvae and placing into a container with soapy water; and/or removing any plant debris after the growing season to eliminate overwintering sites for adults. Insecticides should be applied as soon as common asparagus beetles are present, and again in late summer through early fall to kill adults before they overwinter. Thorough coverage of all plant parts is important in suppressing populations.

 

 

 

Goldenrod Soldier Beetles

–by Dr. Raymond Cloyd

Hordes of goldenrod soldier beetle, Chauliognathus pennsylvanicus, adults are now feeding on goldenrod (Solidago spp.) (Figure 1) and other flowering plants. Adults are extremely abundant feeding on the flowers of wild onion (Allium spp.) (Figure 2), and can also be seen feeding on linden trees (Tilia spp.) in bloom. Adults, in fact, can be seen feeding and mating simultaneously. The goldenrod soldier beetle is common to the western and eastern portions of Kansas.

Fig 1. Goldenrod Soldier Beetle Adults Feeding On Goldenrod Flowers (A.–Raymond Cloyd, KSU)

Fig 2. Goldenrod Soldier Beetle Adults Feeding on Wild Onion Flowers (A.–Raymond Cloyd, KSU)

 

Adults are about 1/2 inch (12 mm) long, elongated, and orange with two dark bands located on the base of the forewings (elytra) and thorax (middle section) (Figure 3). Adults are usually present from August through September. Adult soldier beetles feed on the pollen and nectar of flowers; however, they are also predators, and will consume small insects such as aphids and caterpillars. Flowers are a great place for the male and female soldier beetle adults to meet, get acquainted, and mate (there is no wasting time in the insect world J) (Figure 4). Soldier beetle adults do not cause plant damage. Sometimes adults will enter homes but they are rarely a concern. The best way to deal with adults in the home is to sweep, hand-pick, or vacuum.

 

Fig 3. Goldenrod Soldier Beetle Adult (Author–Raymond Cloyd, KSU).

Fig 4. Goldenrod Soldier Beetle Adults Mating (A.–Raymond Cloyd, KSU)

 

Adult females lay clusters of eggs in the soil. Each egg hatches into a larva that is dark-colored, slender, and covered with small dense hairs or bristles, which gives the larva a velvety appearance. The larva resides in soil feeding on grasshopper eggs. Occasionally, the larva will emerge from the soil to feed on soft-bodied insects and small caterpillars.

 

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