Kansas State University

–by Dr. Raymond Cloyd — Horticultural Entomology

Squash vine borer, Melitta curcurbitae, larvae feed on squash, pumpkin, cucumber, and muskmelon plants. Adults are moths that are 5/8 inches long, orange-red, with gray bands and three to four black markings along with orange-red hairs on the abdomen (Figure 1).

Figure 1. Squash Vine Borer Adult

Adults are active during the day with females laying eggs at the base of plants near the soil. Eggs are 1/30 inches in diameter, red-brown, and flattened (Figure 2).

Figure 2. Squash Vine Borer Eggs At Base of Plant

A single female can lay up to 200 eggs during her lifetime. Larvae that emerge (eclose) from the eggs are white, with a dark head capsule. Young larvae are 1/4 to 3/4 inches in length and taper toward the end of the abdomen. Mature or fully-grown larvae are 1 to 1-1/2 inches long (Figure 3).

Larvae that emerge (eclose) from eggs immediately tunnel into the base of plants and feed for approximately 30 days inside the plant

Figure 3. Mature Squash Vine Borer Larva inside Plant Stem (Raymond Cloyd, KSU)

Figure 4. Squash Vine Borer Larvae Collected From Two Pumpkin Plant Stems (Raymond Cloyd, KSU)

stem. The larvae increase in size as they mature. There is usually one larva per stem; however, multiple larvae may be present in a single stem. On July 24, 2021, we found over 20 larvae in two pumpkin plant stems (Figure 4). It was awesome J. Mature larvae emerge from plant stems, burrow into the soil and construct brown, silken cocoons for overwintering. Squash vine borer overwinters as a pupa in the cocoon located 1 to 2 inches deep in the soil. In early spring, adults emerge from the soil. There is one generation of squash vine borer in Kansas.

During this time of year, squash vine borer larvae are feeding within the internal vascular tissues, inhibiting the ability of plants to take-up water and nutrients. Consequently, you may notice sudden wilting of vines and/or plants collapsing (Figure 5). Once larvae are inside the plant, there is not much you can do to manage squash vine borer and prevent plant damage. The tunnels inside infested plants are filled with

Figure 5. Plant Wilting Due To Feeding By Squash Vine Borer Larvae (Raymond Cloyd, KSU)

Figure 6. Frass Associated With Squash Vine Borer Larva in Plant Stem (Raymond Cloyd, KSU)

moistened frass (fecal matter) (Figure 6). Yellow-green sawdust-like frass may also be found around feeding sites at the base of vines or plants, which is a direct indication that larvae have entered the plant.

Because larvae are feeding inside the plant there is not much that can be done to kill the larvae. However, there are plant protection strategies that can be implemented during the remainder of the growing season such as, sanitation and physical control.

Sanitation: remove and dispose of all wilted plants before larvae exit and enter the soil. Discard all plant debris, including vines and fruits after harvest.

Physical control: rototilling in fall will kill squash vine borer pupae directly or cause the pupae to reside on the soil surface where they are exposed to cold weather or predation by birds. In addition, the process of deep plowing may bury the pupae deeper in the soil profile, which may inhibit adult emergence from the soil. Another technique that may have limited use in large plantings, but may be an option for smaller plantings, is to locate infested stems and vines, and create slits at the base of the plant. Then, tweezers may be used to remove larvae from inside the plant stem. Larvae should be killed and the plant base covered with moist soil and mulch, which will stimulate the production of secondary vines and/or root growth, thus helping the plant to re-establish. The previous technique will only be effective if there are one or two squash vine borer larvae inside the plant stem.

For more information on how to manage the squash vine borer, refer to the following extension publication:

Squash Vine Borer (MF3309 July 2016)

http://www.bookstore.ksre.ksu.edu/pubs/MF3309.pdf

–by Dr. Raymond Cloyd

      Yellowstriped Armyworm, Spodoptera ornithogalli

Ashgray Blister Beetle, Epicauta fabricii, Adults

Tomato and Tobacco Hornworms, Manduca quinquemaculata and M. sexta

Striped and Spotted Cucumber Beetle, Acalymma vittatum and Diabrotica undecimpunctata, Adults

Whiteflies

Twospotted Spider Mite, Tetranychus urticae

Bagworm, Thyridopteryx ephemeraeformis

–by Dr. 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 to 1/2 to 3/4 inches 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 eggs on the underside 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. Young nymphs have a pale-green abdomen (Figure 2) and tend to gather near the eggs they emerged from. Older nymphs are gray (Figure 3) and tend to distribute themselves over the entire plant. Nymphs are 3/16 to 1/2 inches long. The nymphs cannot fly because they do not have fully developed wings.

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

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

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

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

Figure 4. Feeding damage caused by squash bug (Raymond Cloyd, KSU)

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 4).

What can you do? Well, 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, and then killing them by placing into a container of soapy water.
5. Apply a contact insecticide such as, potassium salts of fatty acids (insecticidal soap) or a mineral-based horticultural oil when the nymphs are present. The smaller nymphs are easier to kill than the larger nymphs. Adult squash bugs 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 suppress squash bug populations.

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

Squash Bug (MF3308 July 2016)

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

–by Dr. Raymond Cloyd — Horticultural Entomology

Green June beetle, Cotinis nitida, adults are flying around in massive numbers near managed and/or unmanaged grassy areas, and occasionally ‘bumping’ into people and objects. Adults are 3/4 to 1.0 inch long, velvety-green, and tinged with yellow-brown coloration. Green stripes with yellow-orange margins extend lengthwise on the front wings (Figures 1 and 2).

Figure 1. Green June Beetle Adult (Raymond Cloyd, KSU)

Figure 2. Green June Beetle Adult (Raymond Cloyd, KSU)

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; however, they really do not look alike.

Green June beetle has a one-year life cycle, overwintering as a mature larva or grub in the soil. Adults typically emerge in late-June and are active during the day, resting at night on plants, in thatch, or in compost. Adults produce a sound when flying that is similar to bumble bees. Adults feed on ripening fruits and corn tassels, and may feed on the leaves of oak and maple trees. Male Green June beetles swarm in the morning, ‘dive bombing’ to-and-fro just above managed and/or unmanaged grassy areas where females are located. The females emit an odor or pheromone that attracts the males. Clusters of beetles may be seen on the soil surface or in grassy areas with several males attempting to mate with a single female. After mating, females lay clusters of 10 to 30 eggs in moist soil with a high content of organic matter. The larvae emerge (eclose) from eggs in approximately two weeks and feed near the soil surface. Larvae are 3/8 (early instars) to 1-1/2 (later instars) long and primarily feed on organic matter in thatch or grass-clippings.

–by Dr. Raymond Cloyd — Horticultural Entomologist

Japanese beetle, Popilla japonica, adults are one of the most destructive insect pests of horticultural plants in landscapes and gardens. Japanese beetle adults are present throughout Kansas feeding on many plants including: roses, Rosa spp., littleleaf linden, Tilia cordata, oak, Quercus spp., Virginia creeper, Parthenocissus quinquefolia, apple, Malus spp., and grape, Vitis vinifera. The plant protection strategies implemented to manage Japanese beetle adult populations are limited, and have been for many years. The primary strategy has been spraying contact insecticides to kill adults, which will reduce plant damage.

Japanese beetle adults are 3/8 to 1/2 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, and 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, resulting in a ‘massive orgy,’ 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. In general, adults will not feed on tissue between leaf veins. 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), chewing holes in flower buds, which prevents flowers from opening or causes petals to fall prematurely.

Figure 5. Japanese Beetle Adults Feeding On Rose Flower (Raymond Cloyd, KSU)

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

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

Spray applications of contact insecticides will kill Japanese beetle adults. However, repeat applications are required, especially when high numbers of adults are present. Pyrethroid-based insecticides containing permethrin, bifenthrin, or cyfluthrin as the active ingredient, will suppress Japanese beetle adult populations. However, these insecticides may also directly harm many natural enemies (parasitoids and predators) and continual use may result in 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

–by Dr. Raymond Cloyd — Horticultural Entomology

Vanhoutte spirea, Spiraea x vanhouttei, plants are blooming (Figure 1), which means the first generation of pine needle scale, Chionaspis pinifoliae, nymphs (crawlers) are active and you need to “take action” now to prevent an infestation on pine trees or shrubs.

Figure 1. Vanhoutte spirea, Spiraea x vanhouttei, in full-bloom (Raymond Cloyd, KSU)

Biology

Pine needle scale females are approximately 1/8 inch (3.2 mm) long and white with an orange portion that tapers on one end (Figures 2 and 3). Males are 1/25 inch (1.0 mm) long and white with a rectangular covering. Males develop into winged individuals that mate with females and then die. Mated females produce a white, waxy covering, which provides protection from exposure to insecticide spray applications. Females lay (oviposit) red eggs underneath the protective covering and then die. Each female pine needle scale can produce up to 100 eggs.

Figure 2. Pine needle scale females on pine needles (Raymond Cloyd, KSU)

Figure 3. Close-up of pine needle scale female (Raymond Cloyd, KSU)

Red nymphs (crawlers) emerge (eclose) from the eggs and crawl out from under the dead female covering. First generation nymphs emerge over a two to three week period in spring and feed on the current or previous year’s pine needle growth. Second generation nymphs of pine needle scale emerge in summer. First-instar nymphs are flat and red, and after molting, second-instar nymphs are yellow to light-orange (Figure 4). After six to eight weeks, pine needle nymphs become mature adults. Pine needle scale nymphs may be dispersed by wind or carried by birds to new locations where the nymphs can infest other pine trees. In addition, pine needle scale nymphs may move onto branches of adjacent trees that are touching. Pine needle scale overwinters as red eggs underneath the covering of dead females. There are two generations per year in Kansas.

Figure 4. Pine needle scale nymphs (Raymond Cloyd, KSU)

Damage

Pine needle scales withdraw plant fluids from the inner tissues or mesophyll layer of pine needles using their piercing-sucking mouthparts. Feeding can cause pine needles to turn yellow and fall from trees. Pine needle scale infestations typically start on the lower branches. Pine needle scale feeding can reduce the growth and vigor of pine trees or shrubs in landscapes. Heavy infestations of mature pine needle scale appear as white flecks on needles (Figure 5). Since the pine needle scale is a hard or armored scale there is no honeydew, which is a clear, sticky liquid produced by soft scales.

Figure 5. Pine needle scales feeding on needles (Raymond Cloyd, KSU)

Management

Scout pine trees and shrubs weekly in spring to detect the presence of pine needle scale red nymphs. Double-sided sticky tape wrapped around branches captures red nymphs, which will help time insecticide applications or high-pressure water sprays. Check the tape weekly from spring through summer using a 10- to 16-power hand lens to look for the red nymphs. You can also attach a white sheet of paper to a clipboard and place under a branch that is shaken. Any red nymphs dislodged from the shaken branch may be seen crawling on the paper.

Branches heavily infested with pine needle scale should be pruned out and removed from the area. In addition, pine trees or shrubs in landscapes that are heavily infested with pine needle scale should be cut at the base, just above the soil line, and removed from the area.

High pressure water sprays can be used to dislodge (remove) the red nymphs from pine trees and shrubs, and are less harmful to beneficial insects. Pine needle scale nymphs do not have a waxy, protective covering, so they are easier to kill with contact insecticides. Contact insecticides such as horticultural oils (mineral-based) should be applied when the nymphs are active in spring and summer, which will help reduce pine needle scale infestations later in the growing season. Insecticide applications targeting the first-generation of nymphs should be made when Vanhoutte spirea, Spiraea x vanhouttei, plants are in flower…right now! Insecticide applications and high pressure water sprays should be conducted every seven to 10 days to kill or dislodge the nymphs that emerge from underneath the dead female covering over a two to three week period. Needles and branches should be thoroughly covered with insecticide applications or high pressure water sprays to effectively suppress pine needle scale populations. Pine needle scale is a hard or armored scale, therefore, systemic insecticides applied to the soil will not protect pine trees and shrubs from infestations.

For more information on pine needle scale, consult the following extension publication:

Cloyd, R. A. April 2021. Pine needle scale: insect pest of pine trees (MF3563)

https://www.bookstore.ksre.ksu.edu/pubs/MF3563.pdf