Kansas State University

–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

–by Dr. Raymond Cloyd

European pine sawfly, Neodiprion sertifer

Spruce spider mite, Oligonychus ununguis

Lilac/ash borer, Podosesia syringae

— Dr. Raymond Cloyd

The larvae (caterpillars) of the Eastern tent caterpillar, Malacosoma americanum, are emerging (eclosing) from their eggs and feeding on the leaves of trees and shrubs (Figure 1).

Figure 1. Eastern tent caterpillar feeding on new leaves (Raymond Cloyd, KSU)

After caterpillar’s emerge from the eggs, they create a distinct white, silken nest (or tent) in the branch crotches of trees and shrubs (Figure 2) including: birch, crabapple, hawthorn, mountain ash, poplar, willow, and flowering cherry, peach, and plum. The nest protects caterpillars from cold temperatures and natural predators.

Figure 2. Eastern tent caterpillar nest (Sean Mills)

Caterpillars are black and have a white stripe extending the length of the body along with blue markings on both sides of the body (Figure 3). There are five larval instars (stages between each molt). Eastern tent caterpillar is one of our earliest caterpillar defoliators in the season, feeding on newly emerged leaves, which can reduce the ability of trees and shrubs to produce food by means of photosynthesis. Although feeding damage may not directly kill a tree or shrub, a decrease in photosynthesis can predispose plants to secondary pests such as wood-boring insects. Leaf quality can influence tree and shrub susceptibility. For instance, black cherry, Prunus serotina, trees grown in the shade are fed upon less by Eastern tent caterpillars due to lower leaf nutritional quality.  

Figure 3. Eastern tent caterpillar (Raymond Cloyd, KSU)

The young or early instar (1^st through 3^rd) caterpillars are active during the daytime and reside in the silken nest at night. During the day caterpillars emerge from the silken nest and feed on plant leaves. On over-cast or cloudy days caterpillars will remain inside the silken nest. The final instar (5^th) caterpillar only feeds at night. The length time of time that caterpillars spend feeding increases 4-fold between the 1^st and 5^th instars. Feeding activity depends on temperature with caterpillars feeding for a longer period of time when exposed to warmer temperatures than cooler temperatures. Eastern tent caterpillar overwinters as an egg mass attached to the branches or small twigs (Figure 4). There is one generation per year in Kansas.

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

The silken nests can be physically removed or disrupted by hand. You can destroy, disrupt, or open-up the silken nest using a rake or a high-pressure water spray. The young exposed caterpillars are susceptible to consumption by birds. However, the later instars are fed upon less because the hairs on the body deter birds from feeding on them.

Spray applications of the bacterium, Bacillus thuringiensis subsp. kurstaki, or spinosad are effective in killing small (young) caterpillars and suppressing minor infestations of Eastern tent caterpillar. These insecticides are stomach poisons so caterpillars must ingest the material to be negatively affected. When caterpillars are mature and approximately 2 inches long, then pyrethroid-based insecticides, such as bifenthrin, cyfluthrin, and lambda-cyhalothrin should be applied. It is important to apply insecticides when caterpillars are active during the daytime to increase exposure to the insecticide. 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 Dr. Raymond Cloyd

Striped and Spotted Cucumber Beetle: Insect Pests of Vegetable Gardens (MF3545)

https://bookstore.ksre.ksu.edu/pubs/MF3545.pdf

Colorado Potato Beetle: Insect Pest of Vegetable Crops (MF3541)

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

Whiteflies: Management in Greenhouse Production Systems (MF3532)

https://bookstore.ksre.ksu.edu/pubs/MF3532.pdf

Elm Leaf Beetle: Insect Pest of Elm Trees (MF3537)

https://bookstore.ksre.ksu.edu/pubs/MF3537.pdf

Cross-Striped Cabbageworm: Insect Pest of Vegetable Crops (MF3505)

https://bookstore.ksre.ksu.edu/pubs/MF3505.pdf

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

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

Insect and Mite Pests of Vegetable Gardens (MF3480)

https://bookstore.ksre.ksu.edu/pubs/MF3480.pdf

List as of: November 9, 2020

–by Dr. Raymond Cloyd

Dormant oils can be applied to certain ornamental plants and fruit trees during the winter to kill insect and mite pests that overwinter as eggs or mature females. Consequently, dormant oil applications can help reduce inputs from insecticides and miticides early in the growing season (spring). The advantages of dormant oil applications include: 1) a wide range of activity against the life stages of mite and scale insect pests including the eggs and 2) relatively minimal harm (toxicity) to humans and other mammals. In general, dormant oils are derived from paraffinic crude oil and are the heaviest of the petroleum-based oil sprays with a low unsulfonated residue (Figures 1 and 2).

Figure 1. Dormant oil product (Raymond Cloyd, KSU)

Figure 2. Close up of label of dormant oil product. Note the unsulfonated residue value is 91% (Raymond Cloyd, KSU)

The unsulfonated residue is an assessment of the compounds remaining after distillation and refining that can harm plants. An unsulfonated residue >92% indicates a highly refined product with less potential for phytotoxicity (plant injury). Dormant oils typically have an unsulfonated residue value <92%.

Dormant oil applications kill the overwintering life stages of cerain mites and scale insect pests (Figure 3)

_{Figure 3. San Jose scale on branch of apple tree (Raymond Cloyd, KSU)}

prior to their becoming active in the spring. Applications are made during winter to deciduous ornamental plants and fruit trees. A 2% to 4% application rate is commonly recommended from early winter through early spring. Dormant oils have contact activity and suffocate the insect or mite pest overwintering life stages by blocking the breathing pores (spiracles) or directly penetrating and disrupting cell membranes. However, dormant oils have minimal residual activity (persistence) once residues dissipate, so thorough coverage of all plant parts is important.

Dormant oils are applied to all plant parts. Therefore, the overwintering life stage of an insect or mite pest must be located on the plant. However, not all insect and/or mite pests overwinter on plants. For example, dormant oil applications are not effective against the twospotted spider mite, Tetranychus urticae, because the mite overwinters as a female in plant debris or mulch. However, the spruce spider mite, Oligonychus ununguis, overwinters as an egg on plants, primarily conifers, such as: arborvitae, hemlock, juniper, and pine. Therefore, dormant oil applications will be effective in killing overwintering spruce spider mites.

Dormant oils are effective in killing the overwintering life stages of certain scale insect pests, especially those that overwinter as first and/or second instars or nymphs (crawlers) on ornamental plants and fruit trees. For instance, euonymus scale, Unaspis euonymi, overwinters as second instar nymphs or mature females on the branches and are susceptible to dormant oil applications. However, scale insect pests that overwinter as eggs; such as, oystershell scale, Lepidosaphes ulmi, and pine needle scale, Chionaspis pinifoliae (Figure 4),

Figure 4. Pine Needle Scale Females (Raymond Cloyd

are less susceptible to dormant oil applications because the eggs are stacked or piled on top of each other underneath the dead female (Figure 4). Consequently, dormant oils cannot penetrate and contact the eggs located underneath the dead eggs or those located in the bottom layer. Therefore, insecticide applications are required in the spring when nymphs emerge (eclose) from the eggs and then start emerging from underneath the dead female scale covering.

Some plants, such as arborvitae, beech, redbud, and certain maples (Japanese, red, sugar, and amur), are sensitive to dormant oil sprays applied to the branches or the trunk. Moreover, the needles of Colorado blue spruce, Picea pungens, can be discolored or change from blue to green following a dormant oil application. Phytotoxicity can be a problem when >4% application rates are used and/or when applications are performed in early fall before dormancy or in late spring at bud-break. Problems affiliated with phytotoxicity are less likely to occur when applications are made in late November through February, which is when most plants are completely dormant.

Dormant oils should never be applied to plants that are stressed because stressed plants are more susceptible to phytotoxicity. For instance, lack of moisture, temperature extremes, sudden drastic changes in the ambient air temperatures after spraying, prolonged windy conditions, and disease or insect infestations may predispose plants to phytotoxicity.

There is a general misconception that insect and mite pest populations cannot develop resistance to dormant oils. However, this is not true. For example, a Christmas tree plantation of Scots pine, Pinus sylvestris, trees were sprayed with dormant oils for over 10 years in succession to “control” pine needle scale. Eventually, the scale population became more and more difficult to “control.” Why? Well, what was discovered was that the scale covers increased in thickness, which prevented the dormant oil from penetrating the outer covering and killing any eggs.

Dormant oil applications performed during the winter can reduce insect and/or mite pest populations during the growing season. Therefore, inputs from insecticide and/or miticide applications can be reduced, which will preserve any natural enemies (parasitoids and predators); thus allowing them to naturally regulate insect and/or mite pest populations.