Kansas State University


Extension Entomology

Category: Greenhouse

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)



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.



ID to last week’s bug

–by Frannie Miller


Harlequin Bug – This is an image of a Harlequin Bug. It feeds on cabbage, broccoli, cauliflower and kale. They injure the plants by sucking the plant juices causing white stipples on the leaves. In small plantings, one good way to control them may be by hand picking the adults and crushing the egg masses. If you want to find out more information about their life cycle or controls consult the Harlequin Buy publication at: https://bookstore.ksre.ksu.edu/pubs/MF3135.pdf

New Extension Publication

–by Dr. Raymond Cloyd

                Insect and Mite Pests of Vegetable Gardens (MF3480 February 2020)


This publication explains how to detect potential problems and how to identify pests in vegetable gardens based on the type of plant damage. A discussion of pest life cycles provides information that can be used to select appropriate plant protection strategies.



Biological Control for Greenhouse Growers

–by Dr. Raymond Cloyd


Enrollment is Now Open!

This 4-hour class consists of pre-recorded lectures and video demonstrations and is intended for greenhouse and ornamental plant growers and others interested in learning about the fundamental concepts of insect biological control methods. It provides introductory content to those growers new to biological control and introduces more advanced methods, including banker plants.


The course is instructed Michigan State University’s online course learning management system, Desire 2 Learn by Heidi Lindberg, Greenhouse and Nursery Extension Educator with MSU Extension. Dr. Raymond Cloyd (Kansas State University Extension) co-authored the content. Participants enrolled in this self-paced course will take a pre-test and a final exam to gauge their learning of the topics. Self-assessment quizzes will engage students with the material throughout the course. The course also provides links to additional resources on pertinent biological control topics.


Course Content

The 4-hours of pre-recorded lecture and video demonstrations are divided into six units:


Unit 1: Introduction to Greenhouse Biological Control

Unit 2: Commercially Available Biological Control Agents

Unit 3: Using Banker Plants in Biological Control Programs

Unit 4: Implementing a Biological Control Program

Unit 5: Interactions of Pesticides and Biological Control Programs

Unit 6: Greenhouse Examples of Biological Control Systems: Application Strategy and Costs


The first unit is an overview of the challenges and opportunities of biological control, how biological control systems work, factors to consider when developing your program, and the importance and methodology of scouting in the greenhouse. The second unit of the course covers the commercially available biological control agents sold in the United States and provides benchmark release rates and facts useful to those releasing biological control agents in the greenhouse. Unit three discusses the four most common banker plant systems for green peach and melon aphids, greenhouse whitefly, and western flower thrips. The fourth unit covers important issues, such as, quality control of biological control agents. Unit five addresses integrating pesticides (including fungicides) with biological control agents. Unit 6 presents examples of biological control programs implemented by growers for wholesale spring bedding plants and greenhouse vegetable operations.


Below is the website to access information associated with the course:



Cost: The cost is $129 per person.


Course offerings: This course is offered twice a year (summer and winter).


Summer Course:

Registration period: May

Course available to students: June-August

Winter Course:

Registration period: November

Course available to students: December-February


Win a $75 gift card: Individuals who paid for the course and completed the pre-test, final exam, and post-course evaluation will be entered into a raffle for one of three $75 gift cards!


Financial Need Scholarships:

There are three scholarships available for those that are interested in the course but do not currently have the financial means to take it. Greenhouse growers interested in the scholarship will be able to apply for it upon registering by writing a short paragraph about why you feel you should be awarded this scholarship and how you plan to use the information you learn in your business or professional endeavors. The applicants and winners will be kept confidential. The cost of the course will be $39.99 for scholarship winners. Scholarship winners will be notified after the enrollment period has passed.


Registration Instructions

To register for this course you will need to create an account, sign in with your email/password, and complete the registration process. Step-by-step instructions are below.


Create your MSU Guest Account/Community ID and Password: Create Your Account

Login to the registration system with your Community ID and Password: Biological Control for Greenhouse Growers

Follow the instructions to register for the course. Upon registration, you will receive a receipt and instructions for accessing the course.

Logging Into the Online Course

Once you have registered, follow the instructions below to login – you will use the same login credentials that you set during registration (your NetID is your email address used during registration and use the same password set during registration).


Go to the Michigan State University’s Online Course System (known as Desire2Learn or D2L): https://d2l.msu.edu/.

Click on the Login button. In the MSU NETID field enter your email address (enter the same email used during registration).

Enter the password you set during registration.

You will be logged into D2L – click on the View All Courses link and you will see the course listed.

*Note: If you need to reset your password go to: https://community.idm.msu.edu/ and select the option for Forgot Password.



If you need technical assistance, please contact Michigan State University Discovery Services. They are available at reachout@msu.edu or 517-353-8700. Tell them you are logging into an MSU Extension online course with an MSU Community ID.



What is my username/NETID?

Your username (or NET ID) is the email address you used to create your account during registration (you use the same email address/password for registering and for taking the course).

What URL do I go to for logging into the course?

Go to: https://d2l.msu.edu/. You will see the Michigan State University at the top of the page.

I received a “not authenticated” response when trying to login – what do I do?

A “not authenticated” message is typically an issue with a password not being entered correctly. To reset your password at any time go to: https://community.idm.msu.edu/ and select the option for Forgot Password. You will receive an email from a sender called “Community ID” with a link to reset your password.

I forgot my password – where can I reset it?

To reset your password at any time go to: https://community.idm.msu.edu/ and select the option for Forgot Password. You will receive an email from a sender called “Community ID” with a link to reset your password.

Who can I call for technical support?

If you need technical assistance, please contact Michigan State University Discovery Services. They are available at reachout@msu.edu or 517-353-8700. Tell them you are logging into an MSU Extension online course with an MSU Community ID.


New Extension Publications Associated with Horticultural Entomology Developed in 2019

–by Dr. Raymond Cloyd


Aphid Management in Greenhouse Production Systems (MF3442)



Oak Leaf Itch Mite (MF2806)



Bagworm: Insect Pest of Trees and Shrubs (MF3474)



Grub Management in Turfgrass Using Insecticides (MF3439)



Scale Insect Pests (MF3457)




Twospotted Spider Mites

–by Dr. Raymond Cloyd

The recent hot weather we are experiencing throughout Kansas is conducive to the development of the twospotted spider mite, Tetranychus urticae (Figure 1), resulting in extensive feeding damage to the leaves of horticultural plants in gardens and landscapes (Figures 2 and 3). Twospotted spider mite is a warm-weather mite with populations commonly active from late spring through early fall. Summer temperatures allow twospotted spider mite females to reproduce rapidly, which helps to overwhelm natural enemy (e.g. predators) populations by producing multiple generations throughout the season.

Fig 1. Close-up of twospotted spider mite adults.

Fig 2. Twospotted spider mite feeding damage on euonymus bush leaves (Auth–Raymond Cloyd, KSU)

Fig 3. Twospotted spider mite feeding damage on tomato leaves (Auth–Raymond Cloyd, KSU)

The management of twospotted spider mite populations involves maintaining plant health by avoiding ‘stress,’ implementing sanitation practices, and/or using pesticides with miticidal activity (miticides/acaricides). First, prevent plants from experiencing moisture ‘stress’ by maintaining proper watering and mulching practices, which will be helpful in minimizing potential problems with twospotted spider mite populations. For instance, inadequate moisture or over fertilizing plants, especially with water-soluble nitrogen-based fertilizers, can enhance development and reproduction of twospotted spider mites.

It is important to monitor for twospotted spider mite populations regularly by shaking plant parts (e.g. leaves, branches, or twigs) onto a clipboard with a white sheet of paper, and then look for the mites crawling around (you can actually see the mites). You can crush the mites on the white sheet of paper to determine if they are a pest or not. For example, plant-feeding spider mites typically leave a green streak when crushed whereas predatory mites leave a red streak.

A quick and effective method of managing twospotted spider mite populations is applying a forceful water spray throughout the plant canopy at least twice per week during the season. Forceful water sprays will dislodge eggs and the motile life stages (larvae, nymphs, and adults). Be sure to direct forceful water sprays toward the leaf undersides where all life stages (eggs, nymphs, larvae, and adults) of the twospotted spider mite are located. The removal of plant debris and weeds eliminates alternative hosts and overwintering sites.

There are a number of pesticides with miticidal activity available to professionals for suppression of twospotted spider mite populations outdoors, including: abamectin (Avid), acequinocyl (Shuttle), bifenazate (Floramite), etoxazole (TetraSan), hexythiazox (Hexygon), potassium salts of fatty acids (M-Pede), and horticultural oils (petroleum, mineral, or neem-based). Homeowners do not have as many options. In fact, the only “true miticide” still available is hexakis or fenbutatin-oxide, however, this active ingredient cannot be purchased alone as the active ingredient is typically formulated with another pesticide (insecticide) such as acephate (Orthene). However, homeowners can apply commercially available insecticidal soaps (potassium salts of fatty acids) or horticultural oils. Always read the label and apply miticides before twospotted spider mite populations are extensive and causing damage. Moreover, be sure to rotate miticides with different modes of action to avoid twospotted spider mite populations developing resistance. If possible, target ‘hot spots’ or localized infestations of twospotted spider mites, which will reduce the potential for resistance developing. Be sure to thoroughly cover all plant parts with spray applications; especially when using pesticides with contact activity. Some miticides such as abamectin (Avid) and etoxazole (TetraSan) have translaminar activity, which means the material penetrates into leaf tissues and forms a reservoir of active ingredient within the leaf. This provides residual activity even after spray residues have dried. Mites that feed on leaves will ingest a lethal concentration of the active ingredient and be killed.

It is important to note that many pesticides used to suppress other insect pests encountered on plants in landscapes and gardens may be harmful to the natural enemies of twospotted spider mite; consequently, resulting in an inadvertent increase in twospotted spider mite populations or secondary pest outbreaks.




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