Extension Entomology

Bagworms

Posted on June 5, 2025June 6, 2025 by Department of Entomology

The time is approaching when the 1/8 to 1/4 of an inch bag of the bagworm, Thyridopteryx ephemeraeformus, caterpillar (larva) will be present on broadleaf and evergreen trees and shrubs. Hence, you should be ready to “take action” against bagworms when they are observed on plants. Bagworm caterpillars (larvae) feed on conifers, but they also feed on a wide range of broadleaf plants, including: elm, flowering plum, hackberry, honey locust, linden, maple, oak, rose, sycamore, and wild cherry. Apply insecticides when bagworms are 1/4 of an inch long or less (Figure 1) to maximize effectiveness of insecticide applications and reduce plant damage.

Figure 1. Young bagworm caterpillar (larva) feeding on plant foliage (Raymond Cloyd).

There are several insecticides labeled for use against bagworms; however, the insecticides commonly recommended to manage bagworm populations early in the season are Bacillus thuringiensis subsp. kurstaki and spinosad. These active ingredients are commercially available and sold under various trade names.

Figure 2. Product containing Bacillus thuringiensis subsp. kurstaki as the active ingredient (Raymond Cloyd).

The bacterium, Bacillus thuringiensis subsp. kurstaki (Figure 2), kills young bagworm caterpillars after they have consumed or ingested the bacterium. The insecticide is sensitive to ultraviolet light degradation and rainfall, which reduces residual activity (persistence). Consequently, repeat applications may be required. Spinosad is the active ingredient in several homeowner products, including Captain Jack’s DeadBug Brew (Figure 3) and Monterey Garden Insect Spray. Spinosad works through contact and ingestion but is most effective when ingested by young bagworm caterpillars. Managing bagworms with these insecticides involves applying the insecticides early in the growing season and making frequent applications to kill the young caterpillars feeding on plant foliage. Apply the insecticides weekly for three to four weeks when bagworms are first noticed to avoid problems later in the growing season.

Figure 3. Product containing spinosad as the active ingredient (Raymond Cloyd).

Figure 4. Arborvitae (Thuja) defoliated by bagworm caterpillars (Raymond Cloyd).

Bagworms typically start feeding on the tops of trees and shrubs. Therefore, thorough coverage of all plant parts and frequent applications are important in managing bagworm populations. Multiple applications are usually required because bagworm caterpillars do not emerge (eclose) from eggs simultaneously. Instead, they emerge over time depending on temperature. In addition, young bagworms may be ‘blown in’ (called ‘ballooning’) from neighboring plants on silken threads. If left unchecked, bagworms can cause substantial plant damage, thus ruining the aesthetic quality of plants (Figure 4). In addition, bagworms can kill plants (especially newly transplanted small evergreens) because evergreens usually do not produce another flush of growth after being fed upon or defoliated by bagworms. For small plantings with minimal bagworm infestations, you can hand remove the 1/8 to 1/4 of an inch bags containing the caterpillars and squish them between your fingers.

For more information on bagworms, you can access and read the following extension publication:

Cloyd, R. A. 2019. Bagworm: insect pest of trees and shrubs. Kansas State University Agricultural Experiment Station and Cooperative Extension Service. Kansas State University; Manhattan, KS. MF3474. 4 pages.
http://www.bookstore.ksre.ksu.edu/pubs/MF3474.pdf

By Raymond A. Cloyd, Professor and Extension Specialist in Horticultural Entomology/Plant Protection

Winged Ants or Termites

Posted on May 28, 2025May 30, 2025 by Department of Entomology

As the weather warms especially after a shower of rain, many homeowners in Manhattan and all across Kansas may notice an unsettling sight: large numbers of winged insects fluttering around inside. Often close to a window or door, these springtime visitors can be reproductive ants or termites, emerging from their colonies to mate and establish new ones. While their sheer numbers can be alarming, understanding the difference between these two common household guests is the first step in addressing any potential concerns.

Winged termites (swarmers or reproductives)

Spot the Difference: Ant or Termite?

Distinguishing between winged ants and termites is crucial, as their presence and potential impact on your home differ significantly. Here are three key characteristics to look for:

Feature	Winged Ant	Winged Termite
Antennae	Elbowed (bent)	Straight, bead-like
Wings	Two pairs, unequal length	Two pairs, equal length
Waist	Thin, constricted	Thick, broadly joined

Comparative drawing of termite and ant features (KSRE Publication MF722 Termites)

Ants: The Organized Neighbors

Ants are social insects that live in colonies, which can be located indoors or outdoors depending on the species. Each colony typically has a queen responsible for producing eggs, and a workforce of sterile females that handle tasks like caring for the young and foraging for food. During warmer months, established colonies sometimes produce additional winged males and females, known as reproductives, which fly off to mate. After mating, the males soon die, while the females shed their wings and attempt to start new colonies elsewhere.

What to Do About Winged Ants:

Seeing a swarm of winged ants can be startling, but it doesn’t necessarily signal a major infestation within your home. These individuals are emerging from dark crack or crevice in the structure. They are most likely discovered near a light source, like a window or door as they try to get outside.

A few stray ants: Simply vacuum them up and dispose of the bag outdoors. They are unlikely to start a colony inside.
A significant indoor swarm: This could indicate a colony is located within your house or very close by. In this case:
- Sanitation is key: Eliminate food sources like crumbs, spills, pet food, and open containers that may attract ants.
- Consider targeted treatments: Indoor-safe insecticide sprays can help reduce populations, but treating the nest directly is the most effective solution. For outdoor nests, concentrated sprays can be more economical. Treat ant trails or the nest itself if you can locate it.
- When in doubt, call a pro: If the nest is inaccessible or the problem persists, a professional pest control operator can provide effective solutions.

Learn More About Ants: For more in-depth information, read the publication from K-State Research and Extension, titled ‘Ants: Structural Pests’ which can be accessed online.

Termites: The Silent Destroyers

Termites

In Kansas, the eastern subterranean termite is the most prevalent and damaging species. These termites thrive in warm, moist environments and are often found in soil, building characteristic mud tubes or tunnels made of soil, fecal matter, and saliva. Termite colonies have a complex social structure with workers (creamy-white, wingless, and blind), soldiers (with distinctive large jaws), and winged reproductives (swarmers). It’s often these swarmers that first alert homeowners to a potential termite problem.

What to Do About Winged Termites:

The presence of termite swarmers indicates an existing termite colony in or around your home. In Kansas, the eastern subterranean termite is the most common and damaging. While the swarmers themselves are not immediately dangerous and are unlikely to establish a new colony indoors unless they find moist soil, their appearance should prompt further investigation.

Vacuum and inspect: Like winged ants, vacuum up any swarmers you find and discard the bag outdoors. Then, carefully inspect your home for other signs of termites, such as:
- Mud tubes: Look for these pencil-width tubes running along foundation walls or wooden structures.
- Mud-filled joints: Check wood framing, paneling, and trim for areas that appear to be filled with mud.
- Damaged wood: Probe wood near the foundation with an ice pick, pocket knife, etc. Soft, easily punctured wood can indicate termite damage.
Professional help is recommended: Termite infestations are often complex and best managed by experienced pest control professionals. They can accurately assess the extent of the problem and implement effective treatment and control measures.

Learn More About Termites: For more in-depth information, read the publication from K-State Research and Extension, titled ‘Termites: Structural Pests’ which can be accessed online.

By understanding the differences between winged ants and termites and knowing the appropriate steps to take, homeowners can effectively address these springtime visitors and protect their homes.

For information that covers general information most common to Kansans, read the publication from K-State Research and Extension, titled ‘Household Pests of Kansas’ which can be accessed online.

More information: Jeff Whitworth, (785) 565-2371, jwhitwor@ksu.edu

Identifying Chinch Bugs and False Chinch Bugs

Posted on May 27, 2025May 30, 2025 by Department of Entomology

Chinch bug activity has been elevated in Kansas the last couple of seasons. Now would be a good time to discuss the differences between chinch bugs (Blissus leucopterus) and false chinch bugs (Nysius sp.). To make proper management decisions, knowing how to correctly identify these insects is critical.

Adults

Adult chinch bugs are 3-4mm long bugs with black bodies and white wings that are kept folded over their backs. Two dark, triangular markings are present near the center of the wings creating a distinctive “X” mark (Figure 1).

Adult false chinch bugs are very similar in appearance, but smaller. Instead of having black bodies, false chinch bugs are brownish-gray with clear wings that lack a distinct “X” mark (Figure 2).

Figure 2. Adult false chinch bug. Note the lack of a dark “X”.

Immature Bugs

Immature chinch bugs are bright red after hatching, darkening to black as they go through a series of 5 molts. A distinct white band will be visible across the nymphs’ bodies until the wing buds become large enough to obscure it (Figure 3).

Immature false chinch bugs are grayish-brown, never bright red, and lack the white band across their bodies (Figure 4).

Damage

Chinch bugs and false chinch bugs are true bugs in the order Hemiptera which means they both have piercing-sucking mouthparts that they use to puncture plant tissue to feed on plant juices. However, the symptoms of feeding appear differently for these two bugs. When chinch bugs feed, digestive enzymes are injected into the plant tissue causing it to break down and discolor (Figure 5). Reddish spots often are present at chinch bug feeding sites. Heavy chinch bug feeding can also cause stunting, wilting and necrotic lesions on plants. False chinch bug feeding, on the other hand, usually has little effect on plants, but extreme numbers of the bugs on a plant can cause wilting and death (Figure 6).

Figure 5. Discoloration caused by chinch bug feeding (Photo Jeff Whitworth).

Figure 6. False chinch bug feeding damage to sorghum.

Be proactive about chinch bug management

Think about chinch bug management before wheat is harvested. Simply relying on rescue treatments for young sorghum fields is not recommended. If possible, avoid planting sorghum adjacent to wheat, particularly if the wheat stand is thin and stressed out. Wheat fields should be scouted for the presence of chinch bugs before harvest to provide an estimate of risk to newly planted sorghum fields. One adult chinch bug or 5 nymphs per foot of row will be a hazard to the borders of sorghum planted nearby. If chinch bug problems are expected, an early planted trap crop of sorghum can be utilized between the wheat and sorghum fields and this trap crop can be sprayed if migrating chinch bugs become numerous. Follow-up sprays will likely be needed if the local chinch bug population is high; 5 chinch bugs per seedling would warrant action. Planting time insecticides and seed treatments can provide some early protection for young sorghum, but their effectiveness deteriorates beyond a few weeks. Additionally, scouting should be done weekly during the growing season. Plants a foot tall through flowering can be damaged by 50 chinch bugs per plant.

Additional details on life history and management recommendations for these two pests can be found in the following Kansas Crop Pest publications.

Chinch Bug: https://bookstore.ksre.ksu.edu/pubs/MF3107.pdf

False Chinch bug: https://bookstore.ksre.ksu.edu/pubs/MF3047.pdf

By Anthony Zukoff, Extension Entomology, Southwest Research and Extension Center

Corn rootworm egg hatch has begun

Posted on May 20, 2025May 23, 2025 by Department of Entomology

To date, corn rootworm degree day accumulation for the northern half of Kansas is not tremendously different compared to the same time last year, and egg hatching should begin in one to two weeks in most locations. In the southern portion of the state, degree day accumulation is slightly behind last year, but egg hatching is underway in most locations, and peak hatch is likely in two to three weeks (Table 1).

Table 1. 2025 corn rootworm degree day accumulation compared to 2024 during the same time period. Calculated using 10 cm max/min ground temperatures provided by KSU Mesonet.

CRW Degree Day Accumulation as of May 19
Location	2024	2025	Difference
Colby	255	292	+37
Hays	332	377	+45
Manhattan	356	323	-33
Garden City	428	415	-13
Meade	560	475	-85
Parsons	373	361	-12

Calculating Corn Rootworm Degree Days

As with all degree-day models, the base temperature, or developmental threshold, will be important for predicting rootworm hatch and emergence. Western Corn Rootworm eggs are laid in summer and overwinter in the soil. The following spring, a threshold soil temperature of 52°F or higher will trigger eggs to develop. This base temperature and the daily 10-cm high and low soil temperatures are used to monitor egg hatch using the formula below. It is important to note that degree day calculations for egg hatch should begin starting January 1 of the current year.

Eggs should begin hatching after approximately 380 degree days have accumulated. Peak egg hatch occurs between 684 and 767 accumulated degree days. Examining corn roots for damage 10 to 14 days following peak hatch is recommended since feeding damage will be fresh and easier to detect.

Why is it important to scout for root damage?

Western corn rootworm resistance to Bt corn continues to be an issue in continuous corn in the United States. Field-evolved resistance was first detected in 2009, and, to date, resistance to every commercially available Bt trait package has been detected in corn-producing areas of the country. However, resistance is not uniform across all corn-growing regions, so be sure to check local conditions when making planting decisions. Given this, evaluating corn roots for rootworm damage during the growing season is highly recommended. Doing so lets you know how well your rootworm management practices are working and provides a way to detect the presence of potential resistance to the Bt hybrid planted.

Details for the process of evaluating corn root damage can be found in the KSRE publication MF845 Corn Rootworm Management in Kansas Field Corn. In short, several plants should be dug up throughout the field, and their roots should be washed well for subsequent evaluation using the Iowa State University 1-3 Node Injury Scale. Digging roots will need to be timed after peak damage from rootworm larvae occurs but before roots begin to regrow, typically late June to early July. Corn rootworm resistance to a Bt protein should be considered if the node injury rating is 1.0 in a field with at least 2 consecutive years use of the same single corn rootworm Bt toxin or if the node injury rating is greater than 0.5 in a field with at least 2 consecutive years use of the same pyramided corn rootworm Bt toxins.

It is important to remember that the best management tool for western corn rootworm is rotation to a different crop; in non-continuous corn, the use of Bt hybrids is not recommended. In continuous corn production, rotating Bt-traited corn annually will help slow the evolution of resistance, but it is important to remember that Bt hybrids are only one of the options for dealing with corn rootworm. Rotation to a non-Bt hybrid combined with soil applied insecticides would be another strategy for continuous corn production. Both practices will be useful for prolonging the efficacy of currently available Bt traits.

More Information: Anthony Zukoff, Extension Entomology – Garden City, azukoff@ksu.edu

Soybean Grower Insect Pest Survey

Posted on May 12, 2025May 15, 2025 by Department of Entomology

Kansas State Department of Entomology researchers want to know which insect pests concern you the most!

One of the research topics covered by the Kim Insect Ecology Lab at Kansas State University focuses on techniques to improve managing and scouting for pests in soybean.

We want to hear about your insect-related concerns to help direct our future research and Extension efforts.

Please take our quick (5-7 minute), anonymous survey: https://kstateentom.fillout.com/t/cMJuQoNEJYus

Your voice gives our research clearer direction in order to better support soybean growers across Kansas.

For more information, contact Nicole Kucherov, nkucherov@ksu.edu.

Kansas State University