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Extension Entomology

Author: Sharon Schroll

SOYBEANS – bean leaf beetles, grasshoppers

–by Dr. Jeff Whitworth

Many fields were sampled throughout southcentral and northcentral Kansas over the last couple of days. There seems to be very few insect pests affecting these soybeans, so far. There are some adult bean leaf beetles, which should be monitored as beans start or continue, setting pods as these beetles can start feeding on these new pods. There are a few adult Decte’s stem borers (fig. 1), but not many oviposition holes could be found yet. The only potential problem detected this week were grasshoppers. Weedy/grassy borders adjacent to many fields are loaded with grasshoppers. These areas are still lush and green so far, thus most grasshopper infested areas are still sufficient for these grasshoppers to feed in so they have not yet migrated to crop fields. However, there are some areas that have been treated with herbicides and thus these weeds are/or have died in these areas. Grasshoppers are/have moved into crops–in this case, soybeans (fig 2-3). Continued monitoring is highly recommended and please do not make a pesticide application “just in case”, and please send me an email if soybean aphids are detected.

Figure 1 Ductes Stem Borer  (Cody Wyckoff)

Figure 2   Grasshopper hiding/ feeding (Cody Wyckoff)

 

Figure 3  “Chewed” Soybean leaf  (Cody Wyckoff)

 

Green June Beetle Adult

–by Dr. Raymond Cloyd

Green June beetle, Cotinis nitida, adults are flying around in massive numbers near managed and/or unmanaged grassy areas, and occasionally ‘bumping’ into people and objects. Adults are 3/4 to 1.0 inch long, velvety-green, and tinged with yellow-brown coloration (Figures 1 and 2).

Figure 1. Green June Beetle Adult (Raymond Cloyd, KSU)

 

Figure 2. Green June Beetle Adult (Raymond Cloyd, KSU)

Green stripes with yellow-orange margins extend lengthwise on the front wings. The underside of the body is distinctly shiny and metallic green or gold. Adults resemble ‘dive bombers’ flying around for several weeks in July. Green June beetle adults are sometimes confused with Japanese beetle (Popilla japonica) adults; however, they really do not look alike (Figures 3 and 4).

 

 

Figure 3. Green June Beetle Adult (Raymond Cloyd, KSU)

 

Figure 4. Japanese Beetle Adult (Raymond Cloyd, KSU)

Green June beetle has a one-year life cycle, and overwinters as a mature larva or grub. Adults generally emerge in late-June and are active during the day, resting at night on plants, in thatch, or in compost. Adults produce a sound similar to that of bumble bees. Adults feed on ripening fruits (Figure 5) and corn tassels, and may feed on the leaves of oak and maple trees. Male beetles swarm in the morning, ‘dive bombing’ to-and-fro just above managed and/or unmanaged grassy areas where females are located. Females emit a pheromone that attracts the males. Clusters of beetles may be seen on the surface of the soil or in grassy areas with several males attempting to mate with a single female, resulting in an ‘insect orgy.’ Mated females that survive the ‘experience’ will lay clusters of 10 to 30 eggs in moist soil that contains high amount of organic matter.

Figure 5. Green June Beetle Adults Feeding On Fruit (Raymond Cloyd, KSU)

 

Mimosa Webworm

–by Dr. Raymond Cloyd

Damage associated with mimosa webworm (Homadaula anisocentra) larvae/caterpillars is now quite prevalent on honeylocust (Gleditsia triacanthos) and mimosa (Albizia julibrissin) trees throughout regions of Kansas. The larvae/caterpillars are 1/2 inch long when fully-grown (Figure 1) and rapidly move backward when disturbed. Caterpillars’ web leaves together on the ends of branches (Figure 2).

Figure 1. Mimosa Webworm Caterpillars Feeding On Leaves (Raymond Cloyd, KSU)

Figure 2. Mimosa Webworm Webbing On End Of Branch (Raymond Cloyd, KSU)

Webbing, in general, 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 (Figures 3 and 4) as the caterpillars skeletonize the leaf tissue. Caterpillars eventually fall from trees on 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.

Figure 3. Mimosa Webworm Caterpillar Feeding Damage (Raymond Cloyd, KSU)

Figure 4. Extensive Feeding Damage Caused By Mimosa Webworm Caterpillars (Raymond Cloyd, KSU)

Regarding management of mimosa webworm, it is too late to apply an insecticide if trees are already heavily infested with webbing because caterpillars are protected from spray applications of insecticides inside the leaf webbing. However, next year (2021), you can manage mimosa webworm caterpillar populations by applying an insecticide when the caterpillars are initially present and exposed to insecticide spray applications. Insecticides that contain the following active ingredients can be used: Bacillus thuringiensis subsp. kurstaki, spinosad, bifenthrin, cyfluthrin, and permethrin. Read the label of each product to ensure that “webworms” are listed. High-volume spray applications are required to contact the caterpillars. If possible, selective pruning can quickly remove isolated or localized infestations of mimosa webworm.

VOLUNTEER WHEAT

–by Dr. Jeff Whitworth

Frequent rains over the last few weeks throughout the eastern half of Kansas have really started germination of volunteer wheat (figures 4 and 5). This is the “green bridge” that most wheat pests rely upon for their existence, from the time last fall’s planted crop matured until this fall’s planted crop germinates. Thus, destroying volunteer wheat can really help mitigate most wheat pests.

Figure 4-5 “Green Bridge” of volunteer wheat (Cody Wyckoff)

Cattail Caterpillars

–by Dr. Jeff Whitworth

Cattail caterpillars are a perennial cause of concern throughout south central and north central Kansas. They are usually found on cattails, thus the name. However, every year some sorghum fields are infested. These infestations are usually most intense around field borders, and most especially in sorghum fields near water, i.e., a creek or pond, etc. The adult is a tan or dusky white, heavy bodied moth, which looks somewhat like a southwestern corn borer moth. The females usually start depositing eggs just about at the whorl stage of sorghum. However, the cattail caterpillar is rarely found within the whorl like “ragworms”, i.e., corn earworms/fall armyworms/etc. are. The cattail caterpillar is mostly found on the leaves themselves but may add to the “ragging” up of the leaves after they unfurl from the whorl (fig. 1) due to their voracious leaf feeding. The cattail caterpillar is a relatively hairy but very distinctive larva with bright orange/white/and black body markings (figures 2 and 3). A relatively high percentage of the older, larger, more mature larvae have been found to be parasitized, thus stop feeding, become very sluggish, and eventually just die from these natural enemies of these caterpillars. There is no established treatment threshold.

Figure 1 “Ragging” up of the leaves (Tom Maxwell)

Figure 2 Cattail Caterpillar (Tom Maxwell)

Figure 3 Cattail Caterpillar feeding on the edge of the leaf (Tom Maxwell)

 

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