Kansas State University

search

Extension Entomology

Category: Greenhouse

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

 

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

 

EPA Clears Up Confusion about Dicamba Products

–by Frannie Miller

This year has certainly been challenging for producers! Dicamba is an herbicide that has been around for years in different formulations, but the newer products of Engenia, ExtendiMax and FeXapan have caused a stir of emotions. I personally get a headache just thinking about all the interesting changes that have occurred.

 

Last week the Ninth Circuit Court of Appeals in San Francisco vacated the federal registrations for Engenia, ExtendiMax, and FeXapan creating lots of confusion for producers who planted dicamba-resistant soybeans and cotton. In response, the Environmental Protection Agency issued a cancellation order for these three products. It states that producers and commercial applicators who purchased these products prior to June 3 can apply them through July 31 according to the label directions, but no further distribution or sale of the products can occur.

 

If you are a producer who is forced to look for alternative products to use for post-emergence weed control in these crops, then check out the June 5, Agronomy eUpdate for suggestions: https://webapp.agron.ksu.edu/agr_social/article_new/federal-court-vacates-registration-of-some-dicamba-herbicide-labels-391-1

 

Fundamentals of Using Soaps as Insecticides

–by Dr. Raymond Cloyd

Insecticidal soaps are classified as biorational or “reduced risk” insecticides and are used in certain situations because they leave minimal residues, are less toxic to humans, and are short-lived in the environment because they degrade rapidly. A soap is a substance derived from the activity of an alkali such as sodium (hard soap) or potassium (soft soap) hydroxide on a fat. In general, fats are a blend of particular fatty acid chain lengths. Soap is a general term for the salts of fatty acids. Soaps may be combined with fish, whale, vegetable, coconut, corn, linseed, or soybean oil. For example, “Green Soap” is a potassium/coconut oil soap that was used widely as a liquid hand soap in public restrooms. It is now available as a hand soap or shampoo, and has been shown to be effective, as an unlabeled insecticide, in controlling soft-bodied insects.

Fig 1. Insecticidal Soap Product (Author–Raymond Cloyd, KSU)

Commercially available insecticidal soaps containing the active ingredient, potassium salts of fatty acids (Figure 1), are used against a variety of soft-bodied insect and mite pests including aphids, scales, mealybugs, thrips, whiteflies, and the twospotted spider mite, Tetranychus urticae. The young life stages (nymphs, larvae, or crawlers) are most susceptible to soap applications. Soaps have minimal activity on beetles and other hard-bodied insects although this is not always the case as certain soaps have been shown to kill hard-bodied insects such as cockroaches. Soaps are effective only when insects or mites mite activity as soap residues degrade rapidly; especially under sunlight (ultraviolet light).

The mode of action of soaps is still not well-documented; however, soaps may kill insect and mite pests in one of three ways. First, soaps may work when fatty acids penetrate through the insect’s outer covering (cuticle) and dissolve or disrupt cell membranes. This interferes with cell integrity causing cells to leak and collapse, destroys respiratory functions, and results in dehydration and death of an insect or mite. Second, soaps may act as insect growth regulators interfering with cellular metabolism and the production of growth hormones during metamorphosis. Third, soaps may block the spiracles (breathing pores), which disrupts normal respiration.

There are varieties of fatty acids; however, only certain fatty acids have insecticidal properties, which is associated with the length of the carbon-based fatty acid chains. Most soaps with insect and mite activity are composed of long chain fatty acids (10 or 18-carbon chains) whereas shorter chain fatty acids (9-carbon chains or less) have herbicidal properties, so using materials that have short chain fatty acids can kill plants. For example, oleic acid, an 18-chain carbon fatty acid, that is present in olive oil and other vegetable oils, is very effective as an insecticidal soap.

Insecticidal soaps may directly and indirectly harm beneficial insects and mites. For example, one study showed that insecticidal soap was directly harmful to the predatory mite, Phytoseiulus persimilis. Another study reported that applying an insecticidal soap at a 4% application rate resulted in 80 to 99% mortality of the predatory mite, Neoseiulus (=Amblyseius) cucumeris.

Fig 2. Dishwashing Liquids (Author–Raymond Cloyd, KSU)

There is a general misconception that any soap or laundry detergent can be used as an insecticide. This is not true. As already mentioned, only a few select soaps have insecticidal properties, but many common household soaps, laundry detergents, and dishwashing liquids including PalmoliveÒ, DawnÒ, IvoryÒ, and JoyÒ (Figure 2), which are unlabeled insecticides, may have some activity on soft-bodied insects when applied at a 1% or 2% aqueous solution. However, reliability is less predictable than soaps (potassium salts of fatty acids) that are formulated and registered as insecticides.

Examples of various dishwashing liquids on insect and mite pests are provided below:

 

1) PalmoliveÒ, DawnÒ, JoyÒ, IvoryÒ, and DoveÒ reduced the numbers of sweet potato whitefly,

Bemisia tabaci; green peach aphid, Myzus persicae; cabbage aphid, Brevicoryne

brassicae; and twospotted spider mite on a variety of vegetable crops.

2) Dawn UltraÒ dishwashing liquid was effective on the German cockroach, Blattella

germanica, causing 100% mortality.

3) IvoryÒ liquid dishwashing soap applied at 0.4 to 3.0% concentrations controlled spider mites,

aphids and psyllids.

4) IvoryÒ liquid dishwashing soap at 1 and 2% concentrations was effective in controlling

aphids, spider mites, psyllids, and thrips.

5) New DayÒ dishwashing detergent applied at 2.0 ml/L provided 95% mortality of silverleaf

whitefly, Bemisia argentifolii (=Bemisia tabaci biotype B), nymphs.

6) IvoryÒ liquid dishwashing soap and TideÒ detergent were effective in reducing populations of

aphids; citrus red mite, Phyllocoptruta oleivora; psyllids; and greenhouse thrips, Heliothrips

haemorrhoidalis, on landscape plants.

 

However, dishwashing liquids and laundry detergents are primarily designed to dissolve grease from dishes and clean clothes; not kill insects and mites. The type of fatty acid, length of the carbon-based fatty acid chain, and concentration in many laundry and dish soaps is not known. In addition, the insecticidal effectiveness of these products may be compromised by the presence of coloring agents or perfumes, which often times leads to inconsistent results. Certain laundry and dish soaps will precipitate or solidify in “hard” water, thus reducing their effectiveness. Furthermore, these materials may cause plant injury by dissolving the waxy cuticle on the leaf surface. Registered, commercially available insecticidal soaps are less likely to dissolve plant waxes than household cleaning products. In addition, plants with pubescent (hairy) leaves may be more susceptible to injury from dishwashing liquids and detergents.

Dishwashing liquids and laundry detergents, like insecticidal soaps, lack any residual activity and thus more frequent applications are required. However, too many applications will harm certain plant types. Moreover, detergents are chemically different from soaps and may cause phytotoxicity (plant injury). In fact, many hand soaps are not necessarily pure fatty acids. Most importantly, these solutions are not registered insecticides. Soap companies do not intend for their products to be used as insecticides as they have not gone through the Environmental Protection Agency (EPA) registration process.

Although some dishwashing liquids and laundry soaps are active on insect and mite pests, they should not be used because they are not registered insecticides. Even more important is that a pest control company will generally stand behind a product when there is a problem. However, if a dish or laundry soap is used and plants are injured—there is no recourse.

 

The Buzz about Asian Giant Hornets

–by Frannie Miller and Sarah Zukoff

The Asian Giant Hornet has created a buzz, since being found in the state of Washington/Canada border. These insects have been nicknamed “murder hornets” by the news media. It is important to remember none of these hornets have been found in the state of Kansas. These impressive hornets are similar to our US hornets in that they are not much more aggressive towards people unless their nest or food source is threatened. They do differ however by having a very potent, painful sting. Multiple stings by the Asian giant hornet would warrant medical attention even if the person were not allergic. The hornets build their nests each year underground in abandoned animal burrows or around the roots of trees making the nests hard to detect.

One cause for concern regarding their presence in the United States is their predatory nature towards honeybees. This hornet could devastate European honeybee colonies who have developed no defense mechanisms. Individual guard bees are no contest for the much larger hornet. Groups of hornets can go into a “slaughter phase” where they decimate an entire hive of bees. Then they will occupy the hive and feast upon the honeybee brood.

 

 

Japanese honey bees have developed a defensive mechanism to deal with the threat. They form a mass around the hornet and buzz their wings to create heat. The generated heat kills the hornet because the honeybees can survive at higher temperatures. Basically, a good depiction might be the thought of sticking the hornet in a honeybee microwave as illustrated in the cartoon.

 

 

 

Sadly, in all of the hysteria, many of our look-alike pollinators have been mistaken for the Asian Giant Hornet. Reports of panic killing of bumble bees, wasps, and others have been observed on various news and social media outlets.

 

The Asian Giant Hornet prefers mountainous valleys and has never been recorded from plains regions of any country. It has not been found in Kansas.

 

 

Subscribe By Email

Get every new post delivered right to your inbox.

This form is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.