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Extension Entomology

Category: Horticulture

ID to last week’s bug

–by Frannie Miller

Picture-winged fly – Picture-winged flies get their name from the distinct ornate color patterns on their wings. It is almost like they are painted. Their body shape kind of reminds you of an ant. Larvae feed on rotten, decomposing vegetation and rotten fruit. These insects can be confused with fruit flies, but do not feed on living plant matter like fruit flies.

Caterpillars in Abundance

–by Frannie Miller

 

This week as I have been out in my own yard and garden I have noticed an abundance of different types of caterpillars. Identification of caterpillars can be difficult because so many of them look really similar, but often if you know what plant they feed upon it will give you a clue.

The first image is of a caterpillar sent to me by a friend asking what it was. She found it feeding on her pansies, which were a hold over plants from spring. These caterpillars are known as pansyworms. They usually grow to be 1 ¼ inches long with a characteristic deep-orange color with black striped sides which feature spines. These caterpillars will take bites out of the leaves, but the resulting variegated fritillary butterfly will add color to the garden.

Panysworm image: Courtesy of Cheryl Boyer

Then I found a few yellowstriped armyworm caterpillars feeding on some of my flowers. I picked them off as I did not want them to feed on those particular plants, but allowed them to feed elsewhere. These caterpillars turn into a somewhat drab grayish-brown moth.

 

Yellow Striped Armyworm

Finally I spotted a mass of small caterpillars feeding on sunflowers in the garden. The sunflowers were not ones I plants and had come up as volunteer so I have decided to let the caterpillars eat on these plants. It is difficult to for me to identify the exact species from a picture, but they will turn into some sort of checkerspot butterfly.

 

I have chosen to not use any insecticides to control these particular caterpillars, but options such as Bacillus thuringiensis subsp. kurstaki (Btk) and spinosad can be used when caterpillars are small. If you are going to use these products, remember to read and follow the label.

Checkerspot Caterpillar

 

Sometimes we don’t notice the caterpillars until they are larger and hand picking may become the best control option.

Insect Predation

–by Frannie Miller

Sometimes you capture an image that tells a story and just needs to be shared. My daughter captured such as image of a soldier beetle feeding on another species of soldier beetle while its mate looks on helplessly. This is a good reminder about the circle of life and how other organisms provide food for each other.

A predator is an animal or organism that naturally preys on others primarily for food. The prey is the animal or organism that is hunted and killed by another for food. It is important to note that every organism plays an important role in our ecosystem as they serve as food sources for other species. Just because an insect is a predator one day does not mean they can’t become prey to a larger organism. Nature has a delicate balance.

In order to be a good predator, insects must be able to search the environment and recognize what is acceptable prey. Then they have to be quick enough to capture the prey and delicately handle it, so it does not escape. If an insect is not an efficient hunter, they could lose out on dinner.

 

Some insects have adaptations which cause them to be better at capturing their food. Examples may include: improved vision, limiting searches to prey rich habitats, development of a clear search image, improved motor skills and modifications to their appendages, which make it easier to capture prey. It is amazing the learning opportunities that come from one image.

 

Resources: The Insect Predation Game: Evolving Prey Defenses and Predator Responses, https://tiee.esa.org/vol/v4/experiments/insect_predation/description.html

Image courtesy of Tessa Miller, Valley Bluebirds 4-H Club

Japanese Beetle Adults Are Here!

–by Dr. Raymond Cloyd

Japanese beetle, Popilla japonica, adults are present throughout most of Kansas feeding on many plants including: roses, Rosa spp.; littleleaf linden, Tilia cordata; Virginia creeper, Parthenocissus quinquefolia, and grape, Vitis vinifera. The ways to manage populations of Japanese beetle adults are limited, and have been for many years, with the application 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. In addition, the larva or grub is a turfgrass insect pest in home lawns, commercial settings, and golf courses.

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).

 

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

Japanese beetle adults 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 grapes (Figures 2 and 3).

Fig 2. Japanese Beetle Adults Feeding On Grape Leaf (Auth–Raymond Cloyd, KSU)

 

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

Plant placement in the landscape and the volatiles emitted by plants are factors that affect adult acceptance for

feeding. Furthermore, 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, in general, do not feed on tissue between leaf veins, resulting in leaves appearing lace-like or skeletonized (Figure 4).

Fig 4. Japanese Beetle Adult Feeding Damage On Leaf (Auth–Raymond Cloyd, KSU)

Adults are most active during warm days, feeding on plants exposed to full sun throughout the day, which may be why roses are a susceptible host plant since 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 5), chewing holes in flower buds, which prevents flowers from opening or causes petals to fall prematurely.

Fig 5. Japanese Beetle Adults Feeding On Rose Flower (Auth–Raymond Cloyd, KSU)

Managing Japanese beetle adult populations involves implementing a variety of plant protection strategies, including: cultural, physical, and applying insecticides. Cultural control involves maintaining healthy plants through proper irrigation, fertility, mulching, and pruning, which are important in minimizing ‘stress’, and may possibly decrease susceptibility. In addition, removing weeds attractive to Japanese beetle adults such as smartweed (Polygonum spp.) may help to mitigate infestations. Physical control involves hand removing or collecting Japanese beetle adults from plants before populations are extensive. 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. This procedure, when conducted daily or every-other-day, for at least three weeks, particularly after adult emergence, may substantially reduce plant damage.

 

Fig 6. Floral Food Lure (Bottom) & Synthetically-Derived Sex Pheromone (Top) Associated W Japanese Beetle Trap (Auth–R. Cloyd, KSU)

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

tential 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, bifenthrin or cyfluthrin as the active ingredient, will suppress Japanese beetle adult populations. However, 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. Furthermore, these insecticides are directly harmful to honey bees and bumble bees. Therefore, apply insecticides 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 to be negatively affected. In addition, if extensive populations are present, plant damage can still occur.

 

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

 

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

 

CARPENTER BEES

–Dr. Jeff Whitworth

A couple folks viewed last weeks carpenter bee photos and thought they were bumble bees. This is a great example then to point out just how important it is to take the best possible photos before sending them in to be ID’d. Please take several closeups from several angles and please place some object beside the specimen, i.e., a penny, pencil, ruler, etc, will work, so we can get an idea of size.  Also very important, where the specimen was found and what was it found on, and how many were at that location and what were they doing-feeding/crawling on the ground, etc. The specimens last week were collected from insulation in an old garage and seemed to have smooth abdomens. See figure 3 for side by side comparison between a carpenter bee vs bumble bee.

Figure 3 carpenter bee (on the left) vs bumble bee (on the right)

Also, for those interested in trapping carpenter bees-please see Dr Phil Sloderbeck’s carpenter bee trap (fig 4). Dr Sloderbeck retired ca.6 years ago as a KSU Extension Entomologist and Southwest Kansas Area Administrator. But, (fig 5)as you can plainly see–Dr Phil is still an entomologist at heart! Happy retirement, Dr Phil, and thank you for the pictures!

Figure 4  bee trap (P. Sloderbeck)

Figure 5  captured 17 carpenter bees (P. Sloderbeck)

 

Wheel Bug

–by Dr. Raymond Cloyd

If you have spent any time outdoors walking around, you may have noticed a very distinct, grotesque looking insect on trees, shrubs, or near homes. The insect is the wheel bug (Arilus cristatus), which is common, and widely distributed throughout Kansas. Wheel bugs, also called assassin bugs, are predators that feed on many insect pests. However, the nymphs and adult can inflict a painful bite if handled by human.

Fig 1. Wheel Bug Adults Mating. Male Is On Top Of Female (Auth–Raymond Cloyd, KSU)

Adult wheel bugs are 1 to 1-1/4 inches long, robust with long legs and antennae, and have a stout beak and large eyes on a narrow head (Figure 1). They are dark-brown to gray and possess a wheel or crest with 8 to 12 protruding teeth-like structures (tubercles) on the thorax that resembles a cogwheel; similar to the dinosaur—Stegosaurus (Figure 2). Wheel bugs have two long, slender antennae that are constantly moving or weaving around. Females are typically larger than males. Females lay eggs that resemble miniature brown bottles with white stoppers (Figure 3). Eggs are laid in clusters of 40 to 200. The eggs are glued together and covered with a gummy cement, which protects eggs from weather extremes and natural enemies (e.g. parasitoids and predators). Egg clusters are located on leaves, or the trunk or branches of trees or shrubs. Nymphs hatch (eclose) from eggs and are bright red with black markings (Figure 4). The nymphs do not have the wheel or crest. The life cycle, from egg to adult, takes three to four months to complete. Wheel bugs are active day and night, and are very shy, tending to hide on leaf undersides. The wheel bug overwinters as eggs with one generation per year in Kansas.

Wheel bugs are voracious predators feeding on a wide-variety of insects, including caterpillars (Figure 5), beetles, true bugs, sawflies, and aphids.

Fig 2. Wheel Bug Adult (Auth–Raymond Cloyd, KSU

 

Fig 3. Wheel Bug Eggs On Leaf Underside (Auth–Raymond Cloyd, KSU)

Fig 4. Wheel Bug Nymph (Author–BugGuid.Net)

 

Fig 5. Wheel Bug Adult Preparing To Attack A Caterpillar (Auth–Raymond Cloyd, KSU)

 

Unfortunately, wheel bugs will feed on beneficial insects such as ladybird beetles and honey bees. The mouthparts are red-brown and resemble a tube or straw that is located underneath the head. The mouthpart extends out when wheel bugs are ready to “stab” prey. Wheel bugs paralyze prey with their saliva that contains a toxic substance, which immobilizes prey within 30 seconds. In addition to feeding on insects, wheel bugs are cannibalistic, and will feed on each other if they cannot locate a food source (prey). What is there not to like about “bugs?” J.

 

Euonymus Scale

–by Dr. Raymond Cloyd

Now is the time year when euonymus scale, Unaspis euonymi, is noticeable on evergreen euonymus, Euonymus japonica, and Japanese pachysandra, Pachysandra terminalis), plants in landscapes. Euonymus scale overwinters as a mated female on plant stems. Eggs develop and mature underneath the scale, and then nymphs (crawlers) hatch from eggs over a two to three-week period. The nymphs migrate along the stem and start feeding near the base of host plants. Nymphs can also infest adjacent plants by being blown around on air currents, which results in infestations not being detected until populations are extensive and damage is noticeable. Leaves eventually become spotted yellow or white (Figure 1). Plants located near structures such as foundations, walls or in parking areas are more susceptible to euonymus scale than plants growing in open areas that receive sunlight and are exposed to air movement.

Fig 1. Euonymus Scale Infestation On Euonymus Plants Located Near Building (Auth-Raymond Cloyd, KSU)

Extensive infestations of euonymus scale can ruin the aesthetic appearance of plants, causing complete defoliation or even plant death. Females are dark brown, flattened, and resemble an oyster shell. Males, however, are elongated, ridged, and white (Figures 2 and 3). Males tend to be located on leaves along leaf veins whereas females reside on the stems. There can be up to three generations per year in Kansas.

Fig 2. Male And Female Euonymus Scale On Leaf (Auth–Raymond Cloyd, KSU)

Fig 3. Close-Up Of Euonymus Scale Female (Brown) And Male (White) (Auth–Raymond Cloyd, KSU)

Cultural practices such as pruning out heavily infested branches, without ruining the aesthetic quality of the plant are effective in quickly reducing euonymus scale populations, especially this time of year. Be sure to discard all pruned branches away from the area.

Insecticide applications should have been applied in May through early-June (now is really too late!) when the nymphs are most active, which will help alleviate problems with euonymus scale later in the season. Insecticide active ingredients recommended for suppression of euonymus scale populations, primarily targeting the nymphs, include acephate; pyrethroid-based insecticides such as bifenthrin, cyfluthrin, permethrin, and lambda-cyhalothrin; potassium salts of fatty acids; and petroleum, mineral, or neem-based (clarified hydrophobic extract of neem oil) horticultural oils. Always check plants regularly for the presence of nymphs, which will help time insecticide applications.

Three to four applications performed at seven to 10-day intervals may be required; however, this depends on the level of the infestation. Euonymus scale is a hard or armored scale, so, in most cases, soil or drench applications of systemic insecticides such as imidacloprid are not effective in suppressing euonymus scale populations. However, the systemic insecticide dinotefuran, due to its high-water solubility (39,000 ppm), may provide suppression of euonymus scale populations when applied as a drench to the soil.        Euonymus scale is susceptible to many different natural enemies (e.g. parasitoids and predators), including: braconid and ichneumonid wasps, ladybird beetles, green lacewings, and minute pirate bugs. However, natural enemies may fail to provide enough regulation to substantially impact extensive populations of euonymus scale. Furthermore, insecticides such as acephate; and many of the pyrethroid-based insecticides, including bifenthrin, cyfluthrin, permethrin, and lambda-cyhalothrin are very harmful to most natural enemies, so applications of these materials may disrupt any natural regulation or suppression.

 

For more information on how to manage euonymus scale and other scale insect pests

refer to the following extension publication:

Scale Insect Pests (MF3457 July 2019)

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

 

ID to last week’s bug

–by Frannie Miller

 

Squash bug – Squash bugs use their piercing-sucking mouthparts to suck the sap out of plants leaves. This feeding can lead to the plants to wilt. These pests prefer to feed on zucchini, winter squash, and pumpkins, but will also attack members of the cucurbit family, such as cucumbers, cantaloupe and watermelon. It is important to detect the presence of these pests early, in order to try to control their population.

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