Kansas State University

–by Raymond Cloyd – Horticultural Entomology

Squash bug, Anasa tristis, females have laid eggs and various stages of the nymphs are present feeding on squash and pumpkin leaves. Squash bug adults are flattened and 1/2 to 3/4 of an inch in length. Adults are dark-brown and have wings with brown-to-black and orange markings along the outer edge of the body (Figure 1). Females lay red-orange eggs on the leaf underside and top of leaves. Nymphs emerge (eclose) from the eggs in seven to 14 days and undergo five instars (stages between each molt) before maturing to adults. First instar nymphs that emerge from eggs have a red head and thorax (middle section) and pale-green abdomen (Figure 2). Second instar nymphs have a black head and thorax and a pale-green abdomen (Figure 3).

Figure 1. Squash bug adult (Raymond Cloyd, KSU)

Figure 2. Young squash bug nymphs (Raymond Cloyd, KSU)

Figure 3. Young squash bug nymphs (Raymond Cloyd, KSU)

Nymphs tend to gather near the eggs after emerging. Older nymphs (3^rd to 5^th instar) are gray (Figure 4) and tend to distribute themselves over the entire plant (Figure 5). Nymphs are 3/16 of an inch long and cannot fly because they do not have fully-developed wings.

Squash bug nymphs and adults use their piercing-sucking mouthparts to withdraw plant fluids from leaves, stems, vines, and fruits. Damage to leaves appears as small, yellow specks that eventually turn brown (Figure 6).

Figure 4. Older squash bug nymphs (Raymond Cloyd, KSU)

Figure 5. Older squash bug nymphs on the stem (Raymond Cloyd, KSU)

Figure 6. Feeding damage caused by squash bug (Raymond Cloyd, KSU)

Below are the plant protection strategies that you can implement to mitigate problems with squash bugs and prevent subsequent plant damage.

1. Check plants for the presence of eggs, nymphs, and adults on leaf undersides at least once per week during the growing season.
2. Destroy eggs, and remove (handpick) nymphs and adults, placing them into a container with soapy water to kill them. Handpick every three to four days.
3. Place a floating row cover over plants to protect them from squash bug nymphs and adults.
4. Position wooden boards throughout the garden, turning them over daily to collect squash bugs hiding underneath. You can kill the squash bugs by placing into a container of soapy water.
5. Apply a contact insecticide when the nymphs are present. The smaller nymphs are easier to kill than the larger nymphs. Contact insecticides are less effective against adult squash bugs because adults have a thickened waxy cuticle (skin) that insecticides cannot adhere to and penetrate. Adults are also protected from insecticide sprays by the leafy plant canopy. Weekly applications of contact insecticides may be required to maintain populations below levels that will prevent plant damage. Thorough coverage of the leaf undersides is important to manage squash bug populations.

For more information on how to manage squash bug populations refer to the following extension publication:

Squash Bug (MF3308 July 2016)

https://www.bookstore.ksre.ksu.edu/pubs/MF3308.pdf

–by Raymond Cloyd, Horticultural Entomologist

Japanese beetle, Popilla japonica, adults are present throughout Kansas feeding on many plants in landscapes and gardens including: roses (Rosa spp), littleleaf linden (Tilia cordata), oak (Quercus spp.), Virginia creeper (Parthenocissus quinquefolia), crabapple (Malus spp.), and grape (Vitis vinifera). The plant protection strategies that need to be implemented to manage Japanese beetle adult populations are limited and have been for many years. The primary stra tegy involves spraying contact insecticides to kill adults, which will reduce plant damage.

Japanese beetle adults are 3/8 to 1/2 of an inch long, metallic green with coppery-brown wing covers, and approximately 14 tufts of white hair along the edge of the abdomen (Figure 1).

Figure 1. Japanese Beetle Adults Feeding On Leaf (Raymond Cloyd, KSU)

Japanese beetle adults 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, an d grapes (Figure 2).

Figure 2. Japanese Beetle Adults Feeding On Grape Leaf (Raymond Cloyd, KSU)

Japanese beetle adults produce aggregation pheromones that attract males and females to the same feeding location, which enhances mating (Figure 3).

Figure 3. Japanese Beetle Adult Males And Females Mating (Raymond Cloyd, KSU)

Adults can fly up to five miles to locate a host plant; however, adults 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, in general, do not feed on tissue between leaf veins. Consequently, feeding on tissue between the leaf veins causes the lace-like or skeletonized appearance (Figure 4).

Figure 4. Japanese Beetle Adult Feeding Damage On Leaf (Raymond Cloyd, KSU)

Adults are primarily active on warm days, feeding on plants exposed to full sun, which may be 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 as food sources are depleted. Japanese beetle adults will also feed on flowers (Figure 5),

Figure 5. Japanese Beetle Adults Feeding On Rose Flower (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 includes proper irrigation, fertility, mulching, and pruning that are important in minimizing plant stress, which may decrease susceptibility to Japanese beetle adult feeding. Furthermore, removing weeds attractive to Japanese beetle adults such as smartweed, Polygonum spp., may help to alleviate infestations. Physical control such as hand removing or collecting Japanese beetle adults before populations are extensive may minimize plant damage. The best time to remove or collect adults is in the morning when ambient air temperatures are typically cooler. Adults can be 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, fall into the liquid, and are subsequently killed. The procedure may reduce plant damage when conducted daily or every-other-day, for up to four weeks.

The use of Japanese beetle traps in landscapes or gardens is not recommended since the floral lure and synthetically derived sex pheromone (Figure 6)

Figure 6. Floral Food Lure (Bottom) And Synthetically-Derived Sex Pheromone (Top) Associated With Japanese Beetle Trap (Raymond Cloyd, KSU)

may attract more adults into an area than would occur normally. In addition, Japanese beetle adults ma y feed on plants before reaching the traps, which increases potential plant damage.

Spray applications of contact insecticides will kill Japanese beetle adults. However, repeat applications are required, especially when high numbers of adults are present. A list of active ingredients in commercially available insecticide products for use against Japanese beetle adults is presented in Table 1. It is important to understand that these insecticides may also directly harm many natural enemies (parasitoids and predators) and repeated use can lead to outbreaks of other pests including the twospotted spider mite, Tetranychus urticae. Furthermore, these insecticides are directly harmful to pollinators including honey bees and bumble bees. Therefore, apply insecticides in the early morning or late evening when bees are less active.

For more information on how to manage Japanese beetle refer to the following extension

publication:

Japanese Beetle: Insect Pest of Horticultural Plants and Turfgrass (MF3488 March 2020)

https://www.bookstore.ksre.ksu.edu/pubs/MF3488.pdf

Table 1. Active ingredients in commercially available insecticide products for use against Japanese beetle adults.

–by Raymond Cloyd, Horticultural Entomologist

We have received numerous inquiries associated with insects feeding on the leaves of rose plants. The insects are sawflies and there are at least two species that attack roses this time of year: the rose slug, Endelomyia aethiops, and the bristly rose slug, Cladius difformis. Rose slugs are the immature or larval stage that eventually becomes a black to yellow-colored adult, which resembles a wasp.

Rose sawfly females create openings or slits along the edges of rose leaves with their saw-like egg laying device (ovipositor) and insert eggs. Larvae emerge from the eggs and resemble small slugs. Larvae are approximately 1/2 of an inch long when full-grown and yellow-green, with an orange head (Figure 1).

Figure 1. Rose Sawfly Larvae Feeding on Rose Leaf (Raymond Cloyd, Kansas State University)

The larvae fall onto the soil surface and pupate. Rose slugs overwinter as pupae in earthen cells that are created by the larvae. Bristly rose slug larvae are pale-green and approximately 1/2 to 3/4 of an inch in length. The body is covered with bristle-like hairs (Figure 2). Both species typically have one generation per year in Kansas.

Figure 2. Bristly Rose Slug Larva Feeding On Leaf Underside of Rose (Raymond Cloyd, Kansas State University)

Rose slug larvae feed on the underside of rose leaves causing the leaves to appear skeletonized (Figures 3 and 4). The larvae create notches or holes on the leaf margins. Bristly rose slug larvae feed on the underside of rose leaves causing leaves to appear skeletonized. However, the larvae create larger holes than the rose slug.

Figure 3. Damage on Rose Plant Caused By Rose Slug Larvae Feeding (Raymond Cloyd, Kansas State University

Figure 4. Damage on Rose Leaf Caused By Rose Slug Larvae Feeding (Author-Raymond Cloyd, Kansas State University)

Small infestations of either the rose sawfly or bristly rose slug can be dealt with by removing the larvae by hand and placing into a container of soapy water. A high pressure water spray will quickly dislodge sawfly larvae from rose plants and they will not crawl back onto rose plants. There are a number of contact insecticides containing various active ingredients that are effective in managing populations of both sawflies. Sawflies are not caterpillars. Consequently, the bacterium, Bacillus thuringiensis subsp. kurstaki, which is the active ingredient in various products (e.g. Dipel^®) has no activity on sawflies because the insecticide is only effective against caterpillars.

–by Raymond Cloyd —  Horticultural Entomology

We are getting close to the time when the 1/8 to 1/4 of an inch bags associated with the bagworm, Thyridopteryx ephemeraeformus, will be present on broadleaf and evergreen trees and shrubs. Therefore, be prepared to take action against bagworms once they are observed on plants. Although bagworm caterpillars primarily feed conifers, they also feed on a wide-range of host plants including many broadleaf plants, such as; elm, flowering plum, hackberry, honey locust, linden, maple, oak, rose, sycamore, and wild cherry. It is important to apply insecticides when bagworms are 1/4 of an inch long or less (Figure 1) to maximize effectiveness of insecticide applications and subsequently reduce plant damage.

Figure 1. Young Bagworm Larva or Caterpillar Feeding On Plant Foliage (Raymond Cloyd, KSU)

Many insecticides are labeled for use against bagworms, however, the insecticides that can be used to manage populations of bagworms early in the season are Bacillus thuringiensis subsp. kurstaki and spinosad. These active ingredients are commercially available and sold under various trade names. The bacterium, Bacillus thuringiensis subsp. kurstaki, is only active on young bagworm caterpillars and must be consumed or ingested to kill bagworm caterpillars. 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. Spinosad is the active ingredient in several homeowner products, including Captain Jack’s DeadBug Brew and Monterey Garden Insect Spray. The insecticide works through contact and ingestion, however, the insecticide is most effective when ingested by young bagworm caterpillars. The key to managing bagworms with these insecticides is to apply the insecticides early and frequently enough to kill the highly susceptible young caterpillars feeding on plant foliage. Applying insecticides weekly for four to five weeks when bagworms are first noticed will reduce problems with bagworms later in the year.

Bagworms commonly start feeding on the tops of trees and shrubs. Therefore, thorough coverage of all plant parts and frequent applications are important in managing bagworm populations. The reason multiple applications are required is that bagworm caterpillars do not emerge (eclose) from eggs simultaneously but emerge over time depending on temperature. In addition, young bagworms can be ‘blown in’ (called ‘ballooning’) from neighboring plants on silken threads. If left unchecked, bagworms can cause substantial plant damage, thus ruining the aesthetic quality of plants. Furthermore, bagworms can kill plants (especially newly transplanted small evergreens), because evergreens usually do not produce another flush of growth after being fed upon or defoliated by bagworms.

If you have any questions on how to manage bagworms in your garden or landscape contact your county horticultural agent, or university-based or state extension entomologist. You can also read the following extension publication on bagworms:

Cloyd, R. A. 2019. Bagworm: insect pest of trees and shrubs. Kansas State University

Agricultural Experiment Station and Cooperative Extension Service. Kansas State University; Manhattan, KS. MF3474. 4 pgs.

http://www.bookstore.ksre.ksu.edu/pubs/MF3474.pdf

–Raymond Cloyd — Horticultural Entomology

There are several insect pests currently feeding on plants in vegetable gardens including:

Colorado potato beetle, Leptinotarsa decemlineata, adults feeding on potato plants (Figure 1);

Figure 1. Colorado potato beetle adult (Raymond Cloyd, KSU)

harlequin bug, Murgantia histrionica, adults mating and feeding on horseradish plants (Figure 2);

Figure 2. Harlequin bug adults mating (Raymond Cloyd, KSU)

and flea beetle adults feeding on potato plants (Figure 3).

Figure 3. Flea beetle adults feeding on potato leaves (Raymond Cloyd, KSU)

There are extension publications for the Colorado potato beetle and harlequin bug available with the links provided below:

Colorado potato beetle: insect pest of vegetable crops (MF3541)

https://bookstore.ksre.ksu.edu/pubs/MF3541.pdf

Harlequin bug (MF3135)

https://bookstore.ksre.ksu.edu/pubs/MF3135.pdf

These extension publications provide information on management strategies that can be implemented to avoid or minimize plant damage associated with Colorado potato beetle and harlequin bug. For flea beetle adults, you can contact your county horticulture agent for information on management strategies including the insecticides that can be applied to manage flea beetle adult populations.

For more information on managing insect pests in your vegetable garden contact your county horticulture agent or a state extension specialist.

–by Raymond Cloyd – Horticultural Entomologyh

Eastern tent caterpillar, Malacosoma americanum, larvae (caterpillars) are emerging (eclosing) from eggs and feeding on the leaves of trees and shrubs. After emerging from the eggs, the caterpillars create a white, silken nest in the branch crotches of trees and shrubs (Figure 1)

Figure 1. Eastern tent caterpillar silken nest (Raymond Cloyd, KSU)

including: birch, crabapple, hawthorn, mountain ash, poplar, willow, and flowering cherry, peach, and plum. The silken nest protects caterpillars from cold temperatures and natural predators.

Eastern tent caterpillars are black with a white stripe that extends the length of the body. In addition, there are blue markings on both sides of the body (Figure 2).

Figure 2. Eastern tent caterpillar larva (Raymond Cloyd, KSU)

Eastern tent caterpillar has five larval instars (stages between each molt). Eastern tent caterpillar is one of our earliest caterpillar defoliators, feeding on newly emerged leaves, which can reduce the ability of trees and shrubs to produce food by means of photosynthesis. Although feeding damage caused by Eastern tent caterpillar may not directly kill a tree or shrub, any decrease in photosynthesis can predispose plants to secondary pests such as wood-boring insects. Leaf quality can influence tree and shrub susceptibility. For example, black cherry, Prunus serotina, trees growing in the shade are fed upon less by Eastern tent caterpillars than those growing in full sun due to a lower leaf nutritional quality.

The young or early instar (first through third) caterpillars are active during the day and reside in the silken nest at night. Caterpillars emerge from the silken nest during the day and feed on plant leaves. Caterpillars remain inside the silken nest on over-cast or cloudy days. The final instar (fifth) caterpillar feeds only at night. The extent of feeding by caterpillars depends on temperature with caterpillars feeding for longer durations when exposed to warmer temperatures than when exposed to cooler temperatures. Eastern tent caterpillar overwinters as an egg mass attached to branches or small twigs (Figures 3 and 4). There is one generation per year in Kansas.

Figure 3. Eastern tent caterpillar egg mass attached to branch (Raymond Cloyd, KSU)

Figure 4. Eastern tent caterpillar egg mass attached to branch (Raymond Cloyd, KSU)

The management of Eastern tent caterpillar involves removing the silken nest by hand or using a rake. In addition, a high pressure water spray will destroy the silken nest. Consequently, any young exposed caterpillars are susceptible to predation by birds. However, the older caterpillars are fed upon less because they have hairs on their bodies that deters birds from feeding on them.

Spray applications of insecticides containing the bacterium, Bacillus thuringiensis subsp. kurstaki, or spinosad, as the active ingredient can be used to kill young caterpillars. These insecticides are stomach poisons so the caterpillars must ingest the material to be negatively affected. When caterpillars are older and approximately 2 inches (5 cm) long then pyrethroid-based insecticides, such as those containing the active ingredients, bifenthrin, cyfluthrin, lambda-cyhalothrin, or permethrin, should be applied. It is important to apply insecticides when caterpillars are active during the day, which will increase exposure to the insecticide spray residues. However, pyrethroid-based insecticides are harmful to pollinators (e.g. honey bees) and beneficial insects. Therefore, do not apply pyrethroid-based insecticides when pollinators are active. For more information on managing Eastern tent caterpillar populations contact your county or state extension specialist.

–by Raymond Cloyd, Horticultural Entomology

We have received a number of inquiries regarding homes being invaded by populations of the clover mite, Bryobia praetiosa. Now is the time of year when clover mites enter homes, apartments, or commercial buildings, with extensive numbers crawling around and causing people to be somewhat concerned regarding how to deal with the problem.

Clover mites typically enter homes and buildings from a southwest exposure. Once inside, clover mites aggregate in large numbers in the corners of homes and buildings (Figure 1).

Figure 1. Clover mites aggregating in the corner of a building (Raymond Cloyd, KSU)

Clover mites are primarily a nuisance mite pest because they do not bite humans. However, clover mites will leave a red stain when purposely or accidently crushed.

Clover mite populations only consist of females as males have never been found. Adult clover mites are 1/30 of an inch long, red, with long, pink front legs (Figure 2)

Figure 2. Adult clover

that are used to distinguish clover mites from other mite pests. Clover mites overwinter as eggs in protected locations and there is usually one generation per year in Kansas. Adults feed on over 200 plant types including: clover, grasses, ivy, honeysuckle, apple, freesia, and elm. Clover mite populations can be extensive in well-fertilized turfgrass located near foundations and their feeding will cause turfgrass to appear silvery or frosty.

The management of clover mites involves the following:

1) Remove turfgrass near building foundations.

2) Place an 18 to 36-inch wide band of an inorganic mulch around the foundation of homes and buildings.

3) Mow turfgrass as short as possible.

4) Avoid over-fertilizing turfgrass, especially with water-soluble, nitrogen-based fertilizers.

5) Remove weeds growing around the foundation.

6) Remove or limit the growth of ivy or other host plants growing around the foundation or walls.

7) Use plants near the foundation that are not typically attractive to clover mites, including: marigold, petunia, geranium, arborvitae, and/or yew.

8) Caulk or seal cracks or openings in the foundation or around window seals.

Clover mites inside homes or building can be vacuumed up, however, be sure to avoid crushing them. Clover mites can be captured on sticky tape (Figure 3)

Figure 3. Clover mites captured on sticky tape (Raymond Cloyd, KSU)

placed near openings such as window seals. Pesticides that contain the active ingredient permethrin can be applied around the perimeter of homes or buildings to kill clover mites, which will reduce the number entering homes and buildings. However, do not apply pesticides inside homes or buildings. If necessary, consult with a pest management professional for recommendations regarding perimeter treatments of pesticides with miticidal activity that will prevent clover mites from entering homes or buildings.

–by Raymond Cloyd — Horticultural Entomology

Hummingbirds feed on nectar from flowers (Figure 1) because they cannot survive exclusively on the sugar water provided in hummingbird feeders (Figure 2). Consequently, hummingbirds feed on insects to obtain protein for muscle and feather development. Insects are an important source of amino acids, fats, fiber, salts, and other nutrients required for a balanced diet. Hummingbirds generally feed on insects that can be easily captured and swallowed, such as; ants, aphids, beetles, gnats, mosquitoes, and certain wasps (Figure 3). Hummingbirds will also eat insect larvae and eggs.

Figure. 1. Hummingbird Feeding On Nectar from Flower (Bird Watching HQ)

Figure. 2. Hummingbird Feeding On Sugar Water from Bird Feeder (Bird Feeder Hub)

Figure. 3. Hummingbird Eating On Wasp (The Spruce)

Hummingbirds can eat between several hundred to a thousand insects in one day although the number of insects consumed varies depending on insect availability, insect type, and the dietary needs of hummingbirds.

Hummingbirds catch insects that are feeding on flowers, grab insects directly in the air, remove insects from spider webs, or snatch insects from the undersides of tree leaves. Hummingbirds cannot dismember their prey because of their body size and long, slender mouthparts (bills). Consequently, hummingbirds swallow insect’s whole.