By Jack Fry, Professor and Commercial Turf Extension Specialist
Grub damage top left, southern masked chaffer larva (top right), and adult beetle (below).
Grub Season is Here
Category: Insects
Kansas Officials Confirm Emerald Ash Borer in Nemaha County
By Pat Melgares, K-State Research and Extension news service
The Kansas Forest Service has confirmed the presence of the emerald ash borer on a private residence in Nemaha County, the second new sighting found in a Kansas county this year.
KFS, working with the Kansas Department of Agriculture and K-State Research and Extension, confirmed a live insect on Oct. 14. Officials say the pest had been suspected in the area for several years, but only recently have they found a live insect, which is required to make the detection official.
Earlier in 2024, state officials confirmed the presence of the emerald ash borer in Lyon County.
The emerald ash borer is an exotic, invasive beetle from eastern Russia and northeastern Asia that likely was brought to the U.S. in infested packing material. The beetle threatens urban and rural forests by killing North American ash species and their cultivars.
KFS officials note that at least 70 million ash trees have already been destroyed due to the emerald ash borer, and as many as 9 billion North American ash trees will eventually be functionally rooted out and destroyed from the continent.
The discovery in Nemaha County makes 15 Kansas counties in which the emerald ash borer has been confirmed, including Wyandotte (2012), Johnson (2013), Leavenworth (2014), Douglas (2015), Jefferson (2015), Atchison (2016), Doniphan (2017), Shawnee (2017), Miami (2019), Jackson (2019), Brown (2022), Osage (2022), Franklin (2023) and Lyon (2024).
See map of current counties affected in Kansas.
Forest officials say landowners should learn the signs and symptoms of emerald ash borer in their ash trees, including thinning canopies. As the feeding progresses, trees may begin to sucker (a process called epicormic sprouting) where branches appear near the trunk or lower canopy. Eventually, small D-shaped holes may appear in the bark.
Landowners are encouraged to create a replacement plan for the ash trees on their property to ensure a continually healthy canopy as ash trees decline. A landscape with many types of trees is more resilient to insect, disease and environmental threats that exist or could occur in the future.
Those seeking treatment or removal of ash trees in a county where the insect has already been detected should consult an arborist. A listing of certified arborists in Kansas is available online.
Landowners, especially those in counties where the insect has not already been detected, are encouraged to report suspected cases of emerald ash borer to the Kansas Department of Agriculture, or to the Kansas Forest Service.
All Kansans are reminded of the recommendation to avoid bringing firewood from another state or county where emerald ash borer has been previously detected. Use local sources for firewood.
The Kansas Forest Service, in partnership with K-State Research and Extension, continues to offer workshops and educational training in counties with detected populations of emerald ash borer, as well as those communities not yet affected by the pest.
More information on resources about treatment of infected trees is available online from the Kansas Forest Service.
Sugarcane Beetle Causing Damage to Turfgrass in SE Kansas
By Raymond Cloyd, Professor and Extension Specialist in Horticultural Entomology/Plant Protection
We have received several inquiries from Southeast Kansas regarding black beetles causing damage to turfgrass. The black beetles are adults of the sugarcane beetle, Euetheola humilis (Burmeister) (Coleoptera: Scarabaeidae). The sugarcane beetle is native to the USA and is also called the rough headed corn stalk beetle.
Sugarcane beetle adults are 1/2 of an inch (13 millimeters) long, black, with distinct punctures or indentations that extend along the length of the body (Figure 1). The front legs have four serrations that allow the adult to tunnel through the soil. Sugarcane beetle adults are active in spring and feed during the night. Adults are attracted to light sources at night. Sugarcane beetle adults walk across the turfgrass in the early morning. Adults tunnel into the soil and remain in the soil during the day, which allows them to avoid predators and exposure to direct sunlight. Sugarcane beetle overwinters as an adult in the soil and there is one generation per year.
In the spring, females can lay between 30 to 60 eggs in the soil during their lifespan and then die after laying eggs. Sugarcane beetle larvae emerge (eclose) from eggs after approximately 10 days, and are white grubs with a red head and six yellow legs. There are three larval instars (stages between each molt) with the third instar larvae 1-1/4 of an inch (32 millimeters) long. Larvae are located in or below the thatch layer.
Larvae and adults can damage turfgrass by feeding on the roots, stems, and leaves (blades). Sugarcane beetle adults cause damage to warm season turfgrasses, such as, bermudagrass and zoysiagrass associated with golf courses, home lawns, and sod farms. In addition, sugarcane beetle adults can damage tall fescue lawns. Adults can also damage turfgrass when tunneling through the soil. In addition, mammals including: armadillos, birds, moles, and raccoons can cause substantial damage to turfgrass when searching for sugarcane beetle larvae and adults.
Sugarcane beetle populations can be managed by properly irrigating and fertilizing turfgrass to maintain health and vigor, which can mitigate damage caused by sugarcane
beetle larvae and adults. Furthermore, turn off all lights in the area at night to avoid attracting adults.
Pyrethroid based insecticides can be applied to manage sugarcane beetle adult populations in turfgrass. Apply insecticides when adults are initially present in the spring. Insecticides are more effective against adults that just emerged from overwintering than adults that are present later in the season.
Mimosa Webworm Causing Noticeable Damage
By Dr. Raymond Cloyd, Professor and Extension Specialist
Mimosa webworm, Homadaula anisocentra, larvae or caterpillars are causing noticeable damage to honey locust, Gleditsia triacanthos, and mimosa, Albizia julibrissin, trees throughout Kansas.
The caterpillars are 1/2 of an inch (12.7 millimeters) long when full grown (Figure 1) and move backward rapidly when disturbed. The caterpillars web leaves together on the ends of branches (Figure 2).
Caterpillars create webs near the tops of trees, which protects them from natural enemies (parasitoids and predators) and insecticide spray applications. Trees heavily infested with mimosa webworm are brown or scorched in appearance (Figure 3).
The caterpillars eventually depart from trees using a silken strand before pupating. Mimosa webworm pupates in bark crevices or the pupae are attached to structures (e.g. buildings). There are two generations per year in Kansas.
It is too late to apply an insecticide this time of year when trees are heavily infested with webbing because the caterpillars are protected from insecticide spray applications inside the leaf webbing. However, next year, you can manage mimosa webworm caterpillars by applying an insecticide when the caterpillars are initially present and exposed to insecticide spray applications. You can use insecticides that contain the following active ingredients: Bacillus thuringiensis subsp. kurstaki, spinosad, bifenthrin, cyfluthrin, and permethrin. Read the label of each product to ensure that “webworms” are listed. Bacillus thuringiensis subsp. kurstaki and spinosad are stomach poisons so mimosa webworm caterpillars must ingest the spray solution on the leaf surface in order to be killed. High volume spray applications should be used so that the insecticide contacts the caterpillars or there are residues on the leaf surface. If feasible, selective pruning quickly removes isolated or localized mimosa webworm infestations.
Now is the Time to Scout for Bagworms
Article derived from KSRE News Story: Now is the Time to Scout for Bagworms
Patience and persistence is key when trying to manage bagworms. Begin scouting in early May, and depending on weather conditions – through early summer.
Once caterpillars emerge, they begin feeding on the host tree or shrub, creating their protective bags. In addition to emergence over time, young bagworms can ‘blow in’ – called ‘ballooning’ – from neighboring plants on silken threads, which increases the importance of treating multiple times during the growing season. Watch both conifers and deciduous trees and shrubs. Although defoliation of deciduous trees and shrubs don’t typically affect long-term health of trees and shrubs, extreme defoliation of conifers can cause stress or kill conifers outright.
Hand removing and destroying bagworm bags is an option for smaller infestations. For larger infestations, the bag provides protection from insecticide treatments, so it’s important to apply applications when the bagworms are young. Apply insecticides weekly when young bagworms are present, up to 5 weeks. Treat windbreaks, Christmas trees, and ornamental landscape trees as soon as bagworms are present to prevent bagworms from causing substantial plant damage. Thorough coverage is important, including penetration into the interior plant canopy and upper branches.
Many insecticides are labeled for bagworms, but timing of application and thorough coverage will ensure the effectiveness of insecticides in managing bagworms. When bagworm caterpillars are small (1/8 to 1/4 of an inch long), products containing Bacillus thuringiensis subspecies kurstaki (Btk) or spinosad as the active ingredient can be effective. These insecticides have minimal direct impact on beneficial insects compared to broad-spectrum insecticides, which could lead to outbreaks of spider mites or scale insects that can cause damage to treated trees and shrubs.
If insecticides are not applied when bagworm caterpillars are small (1/8 to 1/4 of an inch in length) then broad-spectrum insecticides, including those containing malathion, acephate, or cyfluthrin as the active ingredients can be applied. Be sure to read the product label and follow directions.
For more information on controlling bagworms, reference the publication, Bagworm: Insect Pest of Trees and Shrubs, written by Dr. Raymond Cloyd.
How to Protect Trees from Elm Leaf Beetles
By Maddy Rohr, K-State Research and Extension News Service
Prevent damage now by using insecticides, says K-State horticulture expert.
Managing plant pests is a common garden task, but Kansas State University horticulture expert Cynthia Domenghini says using preventive methods in the fall also is important.
“There are typically two generations of elm leaf beetles each year,” Domenghini said. “They overwinter as adults and emerge from their protective shelters in early spring. As elm trees develop leaves, the beetles move in and females begin laying eggs.”
Young Elm Leaf Beetle larvae are dark-colored, hairy grubs. Older larvae are yellow with two long, dark stripes. Adult beetles have green and yellow stripes.
“Larvae hatch and spread throughout the tree to feed. Larvae reach maturity within four weeks and seek shelter to pupate,” Domenghini said. Larvae may travel to the bottom of the tree or in cracks of bark.
Domenghini said larvae cause most of the damage by skeletonizing leaves of elm trees. Adult beetles chew holes through the leaves resulting in a change of color to brown and dropping.
Preventive methods include several insecticides. Healthy trees that have not been greatly affected should not be sprayed in the fall.
Larvae and adult sprays include acephate (Acephate, Orthene), spinosad (Natural Guard Spinosad, Conserve, Captain Jack’s Dead Bug Brew, Monterey Garden Insect Spray), lambda cyhalothrin (Scimitar, Spectracide Triazicide).
Domenghini and her colleagues in K-State’s Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining home landscapes and gardens. The newsletter is available to view online or can be delivered by email each week.
Mimosa and Fall Webworm Damage in Trees Throughout Kansas
By Raymond Cloyd, Professor and Extension Specialist
Mimosa Webworm
Damage associated with mimosa webworm, Homadaula anisocentra, larvae/caterpillars is quite noticeable on honey locust, Gleditsia triacanthos, and mimosa, Albizia julibrissin, trees throughout Kansas.
The larvae/caterpillars are 1/2 of an inch long when full–grown and move backward rapidly when disturbed.
Caterpillars’ web leaves together on the ends of branches. Webbing typically starts at the tops of trees and protects caterpillars from natural enemies (parasitoids and predators) and insecticide spray applications.
Heavily infested trees are brown or scorched in appearance because the caterpillars skeletonize the leaf tissue. Caterpillars eventually leave trees using a silken strand before pupating. Mimosa webworm pupates in bark crevices or pupae are attached to structures (e.g. buildings). There are two generations per year in Kansas.
It is too late to apply an insecticide this time of year when trees are heavily infested with webbing because the caterpillars are protected from insecticide spray applications inside the leaf webbing. However, next year, you can manage mimosa webworm caterpillar populations by applying an insecticide when the caterpillars are initially present and exposed to insecticide spray applications.
You can use insecticides that contain the following active ingredients: Bacillus
thuringiensis subsp. kurstaki, spinosad, bifenthrin, cyfluthrin, and permethrin. Read the label of each product to ensure that “webworms” are listed. Bacillus thuringiensis subsp. kurstaki and spinosad are stomach poisons so mimosa webworm caterpillars are killed after ingesting the spray solution on the leaf surface. High-volume spray applications are required so that the insecticide contacts the caterpillars or there are residues on the leaf surface.
Selective pruning, if possible, can quickly remove isolated or localized early infestations of mimosa webworm.
Fall Webworm
The fall webworm, Hyphantria cunea, second generation is now present throughout most of Kansas with nests present on trees, such as, hickory and walnut.
Fall webworm nests consists of silk webbing that encloses the ends of branches and leaves. Fall webworm larvae or caterpillars are pale-green, yellow to nearly white, with two black spots on each abdominal segment. Caterpillars are covered with long, white hairs.
Fall webworm caterpillars feed on a wide-range of trees, including: birch, cherry, crabapple, elm, maples, hickory, pecan, mulberry, walnut, and willow. Fall webworm caterpillars, unlike caterpillars associated with the eastern tent caterpillar, Malacosoma americanum, remain within the enclosed nests and do not venture out to feed.
Caterpillars consume leaves, resulting in branches with only webbing attached that contains fecal deposits (frass) or ‘caterpillar poop’. The nests will eventually dry-up as the caterpillars transition into pupae, with adults eventually eclosing (emerging) from the pupae later on in the growing season.
At this time of year, feeding by fall webworm caterpillars is not directly harmful to trees, especially larger trees. The most effective method of managing fall webworm infestations is to prune-out the nests that enclose the caterpillars, place into a plastic bag, and dispose of immediately. Insecticide spray applications are not be effective in managing fall webworm infestations because the caterpillars remain in the nests while feeding, which reduces exposure to spray residues. If insecticides need to be applied, for whatever reason, use high-volume spray applications that penetrate the protective nests, or use a rake to disrupt or open-up the nests so that insecticide sprays contact the caterpillars.
Articles originated from the Kansas State University Extension Entomology Newsletter
Entomology Department Insect Diagnostics
By Anthony Zukoff, Extension Associate, Entomology
The Entomology Department’s Insect Diagnostics service continues to accept digital identification requests. Our extension specialists’ areas of expertise include home and structural pests, horticultural and garden pests, pests of medical and veterinary importance, agricultural pests as well as general “what’s this bug?” requests. Members of the public seeking assistance identifying an insect or insect related problems can access the Insect Diagnostics ID Request Form online.
After providing observation information such as location and date of the sighting, followed by answering a set of questions intended to help with the identification process, one can then upload up to 3 photos and submit the form. The inquiry is then forwarded on to one of the entomology extension specialists. Within a few days, usually less than two, the identity of the insect along with appropriate life history information and/or control measures is then sent to the client by email or phone.
The online submission process takes only a few minutes and can be accessed with desktop computers and mobile devices. If you need insect identification assistance, submit a request at https://entomology.k-state.edu/extension/diagnostician/. Any questions about the program can be submitted to Insect Diagnostics Program Coordinator, Anthony Zukoff at azukoff@ksu.edu.
Got Plant Questions? The K-State Plant Disease Diagnostic Lab Has Answers.
By Chandler Day, Associate Diagnostician, K-State Plant Disease Diagnostic Lab
A quality diagnoses starts with a quality sample. A sample can be physical plants or digital images of plants. Digital images are a great screening tool to determine if a physical sample is required for diagnoses. In order to make a diagnosis, the quality of the images and/or samples is extremely important. Follow these tips for submitting your plant health questions. If you ever have questions about a plant problem, how to collect and/or ship a sample, feel
free to call or email us.
Inform. Collect. Ship.
Inform:
Send photos and background information to clinic@ksu.edu!
Three types of high quality digital images are an excellent way to pre-screen plant health issues.
- Symptoms up close (Fig. 1)
- Take zoomed in photos of the problem/symptoms.
- Ensure the image is in focus by tapping the image before you take the shot.
- Examples of symptoms: leaf spot, branch die-back, sunken tissue, scorched leaves.
- Entire plant. (Fig. 2.)
- Take photos of the entire plant that includes all plant parts from soil level to the top of the plant.
- Ensure the symptoms are still visible in this type of image.
- Example: whole tree or shrub (trunk/base to top of crown).
- Landscape pattern. (Fig. 3.)
- Stand back and capture the entire landscape where the plant resides.
- Include in the photo the surrounding plants, concrete, rocks, drain spouts, or whatever else is near the symptomatic plant. Don’t worry if the symptoms cannot be seen in this type of image.
- The importance of this image is not to capture the symptoms on the plant but to capture the landscape. This gives us look at how the affected plant is growing within the site and if there are any site issues that might be contributing to the problem.
Useful background information:
- Site history:
- Soil types, drainage, slope, sunny or shady problem areas, previous construction activity, proximity to structures such as roads or sidewalks, etc.
- Irrigation practices:
- Frequency of irrigation, length of time, irrigation application method (sprinkler, drip, hand held hose), time of day
- Chemical history:
- Pesticide usage and timing, fertilizer applications, etc.
- Pattern on plant:
- Describe the problem. Are symptoms on new or old growth? Top or bottom of plant?
- Pattern in landscape:
- One host or multiple hosts? Other plants in the landscape showing similar symptoms?
- Timing:
- When did the symptoms occur: All at once? (i.e. after a storm?) Slowly over time?
Collect:
- Complete the sample submission form with as much information as possible.
- Send a “healthy” plant and a “sick” plant.
- Submit entire plants when possible including roots. (EX. Tomatoes, annuals, turf grass, etc.)
- DIG up plants. Do NOT pull up plants as this can damage the roots.
- Bag roots separately and then place entire plant into larger plastic bag.
- Do NOT add water or use paper bags. These degrade the sample quality and affects the diagnostic process.
- For specific collection guidelines, go to the K-State Plant Disease Diagnostic Lab webpage, scroll down to where it says collection tips, and use the arrows on the right hand side to navigate to the appropriate collection strategy.
Ship:
- Collect and ship samples on the same day. If this is not possible, store plants in plastic bags in the refrigerator until shipping is possible.
- Ship plants overnight using UPS or FedEx. UPS can take up to 14 days even with 2 day priority shipping.
- Ship on or before Wednesday to avoid weekend storage.
The K-State Plant Disease Diagnostic Lab is here to help you identify your plant health problems. If you ever have questions about a plant problem, how to collect and/or ship a sample, feel free to call or email us.
K-State Plant Disease Diagnostic Lab
4032 Throckmorton PSC
1712 Claflin Road
Manhattan, KS 66506
clinic@ksu.edu
785-532-6176
Japanese Beetle Activity
By Raymond Cloyd, Horticultural Entomology/Integrated Pest Management
Japanese beetle, Popilla japonica, adults are present throughout Kansas feeding on many plants in landscapes and gardens, including: roses (Rosa spp), littleleaf linden (Tilia cordata), oak (Quercus spp.), Virginia creeper (Parthenocissus quinquefolia), crabapple (Malus spp.), grape (Vitis vinifera), and common garden canna (Canna x generalis).
The strategies to manage Japanese beetle adult populations are limited and have been for many years. The primary strategy involves spraying contact insecticides to kill the adults in order to reduce plant damage.
Japanese beetle adults are 3/8 to 1/2 of an inch long, metallic green with coppery-brown wing covers. There are approximately 14 white tufts of hair along the edge of the abdomen. Japanese beetle adults live up to 45 days feeding on plants over a four-to-six-week period. Adults feed on many horticultural plants including: trees, shrubs, vines, herbaceous annual and perennials, vegetables, fruits and grapes.
For more information including how to manage Japanese beetle adult populations, read the latest Kansas Insect Newsletter: https://entomology.k-state.edu/doc/extension-newsletters/2023/KSInsectNewsletter%2010.pdf
