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Extension Entomology

Sorghum Pests

Posted on by Sharon Schroll

–by Jeff Whitworth — Field Crop Entomology

 

Sorghum is really struggling across north and south-central Kansas, due to the hot dry conditions. Much is, or just has, started to head out and because of these hot /dry conditions we are seeing quite a lot of incomplete or nonuniform development, even within fields. This makes management decisions for “headworms” even more difficult– but fortunately, at least so far, “headworm” populations have not been much of a problem. Remember, sorghum is vulnerable to “headworm” feeding mainly between flowering and soft dough. We are continuing to see sorghum aphids (sugarcane aphids) migrate into Kansas, as EVERY field monitored in the last 7 days had various levels of infestation, from winged females just starting to produce nymphs (see fig. 1), to fields which have been infested for a week or two (see fig. 2), to a few fields that have substantial populations (see fig. 3 by Marvin Pipes). So far, beneficials seem to be helping to keep most of these aphid populations below treatment thresholds. However, monitoring should continue as these aphids will continue migrating into the state until the advent of much cooler weather.

Figure 1: Winged female sugarcane aphid + nymphs

Figure 2: Sugarcane aphid non-winged adults and nymphs

 

Figure 3: Substantial sugarcane aphid infestation

Biting Flies (horn, stable, horse and deer flies)

Posted on by Sharon Schroll

–by Cassandra Olds — Livestock and Veterinary Entomology

 

Biting flies (horn, stable, horse and deer flies) are a common problem encountered by horses. Animals under attack can exhibit a number of fly worry behaviors including skin twitching, leg stamping, tail swishing and general agitation. Horses trying to escape from flies can stampede and injure themselves so effective fly control is essential! Although pyrethroid based sprays can kill flies on horses, a study carried out this summer determined that their repellant effects wore off within 4 hours. In contrast, physical barrier protection through a full body fly sheet, fly boots and fly mask, reduced fly worry behavior by 80-90% and was sustained throughout the day. Physical barriers inhibit the ability of the fly to reach the host skin and take a blood meal, not only does this reduce fly worry but also reduces the risk of pathogen transmission.

Horse flies (Figure 1 A and B2) and deer flies (Figure 1 B1) both have brightly colored eyes although, the larger black horse fly (Tabanus atratus) (Figure 1 C) can also often be seen. The fly in Figure 1 C was observed trying to feed off a fully covered horse but was unsuccessful and moved onto an uncovered horse nearby where it fed successfully despite attempts from the horse to remove it! Horn flies (Figure 1 D-G) are commonly found on cattle although horses can also be a suitable host. These flies feed 20-30 times a day causing significant fly worry. Horses can often be observed with saliva patches on their back around horn flies (Figure 1 E) indicating repeated attempts to get rid of flies. Horn flies tend to feed together as a group on the neck, withers and belly. Scarring can commonly be seen under the belly in horses with large numbers of flies sustained over a long period. Fly sheets with belly coverings are most effective against horn flies. Stable flies (Figure 1 H) have a strong preference for horse legs, especially front legs. Covering legs though the use of fly boots reduces stamping which can cause stress on the leg and hoof. Best fly protection can be achieved by selecting a well fitted sheet that covers as much of the body as possible (Figure 2). Fly boots come in a variety of types and it is best to select on which can cover as much of the lower leg as possible. Face masks are especially useful in later summer when flies attempt to feed around the horse eye, nose and mouth which can cause irritation and sores. As with all horse gear, check daily for correct fit or signs of rubbing or discomfort!

Figure 2: Example of a well fitted full body fly protection

 

Soybean Pests

Posted on by Sharon Schroll

–by Jeff Whitworth — Field Crop Entomologist

The ongoing hot dry conditions seem to be starting to significantly stress many dryland crops. Then when you add in the stress of an insect pest it can really cause problems. Right now, blister beetles and Dectes stem borers are very active and causing concerns. Many growers seem to be confusing the two–adult Dectes with blister beetles–with good reason, as some blister beetle adults are similarly colored and shaped somewhat like adult stem borers. The two blister beetles most commonly confused with Dectes stem borer adults are shown here at the top, and just above (see fig. 1) a stem borer adult (photo by JR Ewing). Blister beetles may cause some defoliation by eating leaf tissue but it is usually insignificant. However, Dectes are currently still depositing eggs in soybean petioles, and have been for 2-3 weeks, where the small larvae hatch and start boring into the stem, most often causing the stem to die (see fig 2). However, the larvae continue this tunneling/boring into the main stem (see fig 3) and eventually end up just below ground where they remain through the winter.  (Figures 2 & 3 pictures provided by Sean Mills)

Figure 1: Two adult blister beetles on the top-adult and adult Dectes stem borer at the bottom left.

Figure 2: Crop damage from Dectes stem borers

 

Figure 3: Tunneling/boring stem damage

 

 

 

 

 

Blister Beetles

Posted on by Sharon Schroll

— by Raymond Cloyd — Horticultural Entomologist

 

If you are growing Swiss chard, Beta vulgaris subsp. vulgaris, in your vegetable garden, you may be encountering leaf feeding damage caused by the adult stage of two blister beetle species: the ashgray blister beetle, Epicauta fabricii (Figure 1),

Figure 1. Ashgray blister beetle adult (Raymond Cloyd, KSU)

and the threestriped blister beetle, Epicauta lemniscata (Figure 2).

 

Figure 2. Threestriped blister beetle adult (Raymond Cloyd, KSU)

Both can cause extensive plant damage (Figure 3) and leave black fecal deposits (“poop”) on plant leaves (Figure 4).

Figure 3. Extensive plant damage to Swiss chard caused by adult blister beetle feeding (Raymond Cloyd, KSU

Figure 4. Fecal deposits (poop) associated with blister beetle adult feeding (Raymond Cloyd, KSU)

The best way to deal with these insect pests is to remove the adults by hand and place into a container of soapy water. Be sure to wear gloves when handling blister beetle adults because they can emit a substance called cantharadin that may cause blisters when in contact with the skin.

 

Video: How to control flies on livestock

Posted on by Sharon Schroll

— by Cassandra Olds — Livestock and Veterinary Entomology

K-State Research and Extension news service  — Released: July 27, 2022

 

In this video, K-State Research and Extension veterinary entomologist Cassandra Olds outlines the best ways to control flies in livestock herds, a problem that she says “plagues most producers most years.”

 

While most people associate flies as one breed, there are actually four types that impact livestock herds: houseflies, horn flies, stable flies and face flies.

 

“Lucky for us, each fly has a preference for where it likes to be on the animal, or not on the animal,” Olds said, noting that horn flies prefer the animal’s back or belly; stable flies are common on the front legs; houseflies hang out around the feed bunk; and face flies are found on the animal’s face.

 

“Each fly can lay 100 eggs every couple days, so over her lifetime, she may lay 500 eggs,” Olds said. “So getting rid of adults is important, but getting rid of the places where they breed is more important. By knowing which fly pest you have, you can look for areas where these flies may be breeding.”

 

View the full video, including Olds’ recommendations for control, at https://youtu.be/CruB4fINMKY

 

 

MORE INFORMATION:

K-State Veterinary Entomology, https://www.veterinaryentomology.org/vetpestx

 

K-State Research and Extension video by Dan Donnert
785-532-5804
ddonnert@ksu.edu

For more information:
Cassandra Olds
colds@ksu.edu

Gorgone Checkerspot

Posted on by Sharon Schroll

–by Raymond Cloyd – Horticultural Entomologist

 

Have you noticed the leaves on your sunflower, Helianthus annuus, plant being fed upon by caterpillars (Figure 1)?

Figure 1. Gorgone checkerspot caterpillars on leaf of sunflower (Raymond Cloyd, KSU)

If so, the caterpillar is the gorgone checkerspot, Chlosyne gorgone. The caterpillar ranges in color from black to orange, with a black head and spines or barbs covering the body (Figures 2 and 3).

Figure 2. Gorgone checkerspot caterpillars (Raymond Cloyd, KSU)

Figure 3. Gorgone caterpillar (Raymond Cloyd, KSU)

The caterpillars feed on sunflowers and other related plants. The caterpillars initially feed in groups (Figure 4)

Figure 4. Gorgone caterpillars feeding on sunflower leaf (Raymond Cloyd, KSU)

whereas later on the mature caterpillars, which are approximately 1.0 inch in length, feed individually (Figure 5). Third instar larvae eventually searches for a place to overwinter.

Figure 5. Mature gorgone caterpillar (Raymond Cloyd, KSU)

If you see caterpillars feeding on sunflower leaves and your plants can tolerate some feeding damage, then just leave them alone as the caterpillars will eventually develop, by means of complete metamorphosis, into beautiful butterflies.

 

Mimosa Webworm

Posted on by Sharon Schroll

–by Raymond Cloyd – Horticultural Entomologist

 

Damage caused by mimosa webworm, Homadaula anisocentra, larvae/caterpillars is prevalent on honey locust, Gleditsia triacanthos, and mimosa, Albizia julibrissin, trees throughout most regions of Kansas. The larvae/caterpillars are 1/2 of an inch long when full-grown (Figure 1)

Figure 1. Mimosa webworm caterpillars feeding on leaves (Raymond Cloyd, KSU)

and rapidly move backward when disturbed. Caterpillars’ web leaves together on the ends of branches (Figure 2).

Figure 2. Mimosa webworm webbing on end of branch (Raymond Cloyd, KSU)

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 (Figures 3 through 5) 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)

Figure 5. Extensive feeding damage caused by mimosa webworm caterpillars (Raymond Cloyd, KSU)

At this time of year it is too late to apply an insecticide when trees are already heavily infested with webbing because 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. High-volume spray applications are required to contact the caterpillars. If possible, selective pruning can quickly remove isolated or localized infestations of mimosa webworm.

Cicada Killer

Posted on by Sharon Schroll

–by Raymond Cloyd — Horticultural Entomologist

We are receiving inquiries regarding large wasps flying around in landscapes and gardens. These large wasps are the Eastern cicada killer, Sphecius speciosus. Cicada killer adults are approximately 2.0 inches long and black with yellow-banded markings on the abdomen. The head and transparent wings are red-brown (Figure 1). Cicada killers are not dangerous, but they are intimidating; especially the males. Cicada killers are solitary wasps, not social wasps like yellowjackets. Adults live up to 75 days from July through September, and feed on flower nectar and plant fluids.

Figure 1. Cicada Killer Adult (Raymond Cloyd, KSU)

A female cicada killer will dig a 6 to 10-inch burrow (1/2 inch in diameter) in the soil; usually in sandy or loose soil. A pile of sand or soil, depending on soil type, will surround the entrance. Afterwards, cicada killer females search for dog days cicada, Tibicen pruinosa, adults located on the trunks and lower branches of trees. The female stings an adult cicada using her ovipositor (egg-laying device), flips the cicada over, straddles the cicada, and then transports the immobilized or paralyzed cicada back to the burrow in the soil (Figures 2 and 3). Each burrow may contain three to four cells with one or two cicadas. The dead cicada serves as a food source for the cicada killer larvae, which are legless and grub-like. A female will lay one egg per cicada if the egg is unfertilized. Larvae that emerge from unfertilized eggs are males whereas larvae that emerge from fertilized eggs are females and are provided with two cicadas. Larvae emerge (eclose) from eggs in two to three days and feed on paralyzed cicadas. The female will eventually cover the burrow, dig another one, and repeat the process. Full-grown larvae overwinter inside silken cases, pupate in spring, and adults emerge from July through August. There is one generation per year in Kansas.

Figure 2. Cicada Killer Female Transporting A Paralyzed Cicada To Her Nest (Raymond Cloyd, KSU)

 

Figure 3. Cicada Killer Adult Female With Dead Cicada

Cicada killers are an urban nuisance pest, especially when large numbers are nesting in bare areas, in turfgrass, or around a structure. People are generally concerned because cicada killers resemble giant yellowjackets or they think cicada killers are the so-called “Murder Hornet”. However, in general, cicada killers will not sting an individual. Wasp and bee female stingers are modified egg-laying devices (ovipositors), so males cannot sting. Females may sting if they going to be stepped on with bare feet or grabbed with bare hands.

Male cicada killers establish aerial territories and patrol for intruders. A male cicada killer wards-off other males that enter his territory and attempt to mate with females. An individual that walks into the territory is typically confronted by a very large wasp hovering in front of the face that ‘zips’ to the side and back. However, after determining that the intruder is not a rival or a threat, the male cicada killer ignores the individual. Nonetheless, an individual walking across a lawn, fairway, or other area where cicada killers are nesting, will experience the same treatment through each male’s territory. Sometimes there can be up to 20 cicada killer males in one area. After females have departed the nest, then males will eventually leave.

Cicada killers are common in areas with bare soil, so mulching, planting ground covers, or sodding may reduce potential problems with cicada killer populations. Cicada killers can be a problem in well-maintained areas such as irrigated and regularly fertilized turfgrass. In addition, cicada killers can be a problem when nesting in areas accessible to or frequented by the public. Applying carbaryl or pyrethroid-based insecticides containing the active ingredients; permethrin, bifenthrin, cyfluthrin, and/or lambda-cyhalothrin to the burrowed (nesting) area may kill females in golf course sand traps. In home yards, cover sandboxes with a tarp when not in use to deter cicada killers. Sand below swings, jungle gyms, or other playground equipment should be replaced with bark mulch or shredded tires.

Managing cicada killers in baseball infields and volleyball courts is more difficult because people with minimal clothing and exposed skin are diving and sliding onto the soil. Consequently, the use of an insecticide may not be an option. However, in the case of a volleyball court, a geotextile fabric placed beneath the sand may create a barrier that prevents cicada killers from creating burrows.

 

 

Garden Webworms

Posted on by Sharon Schroll

–by Jeff Whitworth — Field Crop Entomologist

Garden webworms (fig. 2) have just about finished feeding on soybeans and/or alfalfa (where they have been much less noticeable). They will pupate in the soil for the next 4-7 days then the moths will emerge to start depositing eggs in acceptable host plants. From a crop perspective this time of year, hopefully they will have little impact as the soybeans have developed far enough that these worms won’t defoliate enough to affect yield. But the really late-planted soybeans or those that may be moisture stressed may still have some concern, so monitoring should include these defoliators starting soon.

 

Figure 2: Garden webworm mature larva (picture by Steve Freach)