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Extension Entomology

Author: Sharon Schroll

Armyworm in Brome and Rye

— by Dr. Jeff Whitworth and Dr. Holly Davis

We have received several calls and emails relative to armyworms feeding in brome and/or rye fields.  Larvae sampled this week are relatively mature and should finish feeding and pupate within the week.  This larval feeding (defoliation) should not impact a healthy brome stand as they just graze on the foliage.  However, rye that is not growing well may have some stand reduction.  Whether feeding on brome or rye, the larvae we sampled should cease feeding within the next 3-4 days, or less.

 

 

 

 

Alfalfa Update — lady beetles, green lacewings, potato leafhoppers, Fall armyworms, green cloverworms

— by Dr. Jeff Whitworth and Dr. Holly Davis

Alfalfa is really living up to its reputation as a ‘sink’ right now for many different insect species, including many beneficials such as lady beetles and green lacewings.  The one and only potentially serious pest that we are still seeing is potato leafhoppers, and they are in densities that exceed treatment threshold in all fields sampled.  These very small, lime green, wedge-shaped insects that move in a herky-jerky manner remove fluid from the alfalfa leaves.  This feeding may also introduce a toxin which initially causes the tips of leaves to turn yellow (hopper burn), but may impact the entire stem, and eventually the whole plant. This can be especially problematic this time of year when the plants need to utilize the foliage to transfer nutrients to the roots before winter.  The potato leafhopper populations will hopefully be diminishing as they don’t overwinter in Kansas and thus should be heading to the southern U.S. soon. Swathing should also help diminish populations.

 

This time of year fall armyworms may move into alfalfa where they can add to the defoliation caused by other chewing insects already present.  Fall armyworms are more commonly thought of as a pest of corn and sorghum.  This time of year those crops are too mature to support the larvae and therefore the adult moths may oviposit in alfalfa.

We also noticed several green cloverworms along with one larva infected with an entomopathogenic fungus.

 

 

For more information relative to insect pest management in alfalfa, please see the KSU 2018 Insect Pest Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/mf809.pdf

Household Pests of Kansas is now available!

–by Dr. Jeff Whitworth and Dr. Holly Davis

Household Pests of Kansas was written to help homeowners and pest managers identify and manage key arthropod pests found in and around Kansas homes including insects, spiders, ticks and more.  This guide includes color photos, descriptions, basic biology, types of damage, and management options.  It is a valuable reference for all Kansas residents.  You can download your copy today, or order your print version from the KSRE bookstore here: https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=526&pubId=21199

 

 

Goldenrod Soldier Beetles

–by Dr. Raymond Cloyd

Hordes of goldenrod soldier beetle, Chauliognathus pennsylvanicus, adults are now feeding on goldenrod (Solidago spp.) (Figure 1) and other flowering plants. Adults are extremely abundant feeding on the flowers of wild onion (Allium spp.) (Figure 2), and can also be seen feeding on linden trees (Tilia spp.) in bloom. Adults, in fact, can be seen feeding and mating simultaneously. The goldenrod soldier beetle is common to the western and eastern portions of Kansas.

Fig 1. Goldenrod Soldier Beetle Adults Feeding On Goldenrod Flowers (A.–Raymond Cloyd, KSU)

Fig 2. Goldenrod Soldier Beetle Adults Feeding on Wild Onion Flowers (A.–Raymond Cloyd, KSU)

 

Adults are about 1/2 inch (12 mm) long, elongated, and orange with two dark bands located on the base of the forewings (elytra) and thorax (middle section) (Figure 3). Adults are usually present from August through September. Adult soldier beetles feed on the pollen and nectar of flowers; however, they are also predators, and will consume small insects such as aphids and caterpillars. Flowers are a great place for the male and female soldier beetle adults to meet, get acquainted, and mate (there is no wasting time in the insect world J) (Figure 4). Soldier beetle adults do not cause plant damage. Sometimes adults will enter homes but they are rarely a concern. The best way to deal with adults in the home is to sweep, hand-pick, or vacuum.

 

Fig 3. Goldenrod Soldier Beetle Adult (Author–Raymond Cloyd, KSU).

Fig 4. Goldenrod Soldier Beetle Adults Mating (A.–Raymond Cloyd, KSU)

 

Adult females lay clusters of eggs in the soil. Each egg hatches into a larva that is dark-colored, slender, and covered with small dense hairs or bristles, which gives the larva a velvety appearance. The larva resides in soil feeding on grasshopper eggs. Occasionally, the larva will emerge from the soil to feed on soft-bodied insects and small caterpillars.

 

Scolia dubia: Parasitoid of Green June Beetle Larvae

–by Dr. Raymond Cloyd

Have you seen large wasp-like looking insects feeding on flowering plants such as wild onion, Allium spp and goldenrod, Solidago spp.? Well, this is Scolia dubia, which is a parasitoid of green June beetle, Cotinus nitida, larvae (grubs) located in the soil. Parasitoids are approximately 3/4-inches long with purple to black wings. The abdomen has red-brown markings and two very conspicuous yellow spots on both sides of the third abdominal segment (Figure 1). The parasitoids may be seen flying in a figure-eight pattern several inches above turfgrass infested with green June beetle larvae. The parasitoid can be seen feeding on goldenrod flowers along with goldenrod soldier beetle, Chauliognathus pennsylvanicus, adults (Figure 2) (see next article).

Fig 1. Adult Scolia dubia Feeding on Wild Onion Flower (Author–Raymond Cloyd, KSU).

 

Fig 2. Scolia dubia Adult Feeding on Goldenrod Flowers Along with Goldenrod Soldier Beetle Adults (A.–Raymond Cloyd, KSU)

Female parasitoids enter the burrow of a green June beetle larva, paralyze the larva by stinging it, and then attach an egg to the underside of the larva. After hatching, the parasitoid larva consumes the dead green June beetle larva. Scolia dubia overwinter as a pupa in a cocoon located at the bottom of the burrow and then emerge (eclose) later as an adult. Adult parasitoids typically emerge (eclose) in middle to late August and feed on flower pollen and nectar. These parasitoids, unlike cicada killer wasps, are not very aggressive and will only sting (at least the females) when handled or stepped on with bare feet.

 

Soybean Update – Green Cloverworms and Stink Bugs

–by  Dr. Jeff Whitworth and Dr. Holly Davis

Probably the most common defoliator of soybeans throughout Kansas, for the past 6-7 years, has been the green cloverworm.  This year has been no exception to that although there have not been the significant densities throughout most of the state as in 2015-2017.  Most green cloverworm larvae are relatively mature or have pupated and the adult moths are, and will continue to be, emerging.  In south central and north central KS, these moths are gaining attention as they congregate around lights at night and can be found hiding under boards, logs, rocks, etc. around soybean and/or alfalfa fields during the day.

 

One point of concern is relative to the next generation of larvae.  The adults that are present now are from the 2nd generation.  In KS, we can have 3 generations/year.  So, current adults may oviposit in alfalfa and soybean fields and the larvae may feed for the next few weeks.  However, both alfalfa and soybeans are far enough along that this late season feeding should not impact yields of either crop.  Another concern is about these moths congregating in and around fields and what that means for next year.  Green cloverworms do not overwinter in KS.  So, wherever they migrate, or are blown, in next summer is where they will initiate infestations.  Therefore, infestations next year have nothing to do with infestations this year.

 

Stink bugs are also causing some concern for soybean producers.  The two most common stink bugs found in KS soybean fields are the brown and green stink bugs.  Both lay eggs in groups or clusters and green stink bug nymphs are red, black, yellow, and green while brown stink bug nymphs are generally just yellow to brown.

 

 

 

 

 

 

After emerging from the eggs, nymphs stay in the same vicinity for the 1st couple of molts and then disperse.  So, sampling in areas with clusters of nymphs will often overestimate the density.  They all have sucking mouthparts but must have tender, succulent tissue to suck the juice from.  Treatment should only be considered while beans are still filling in the pods.  Stink bugs have a wide host range of plants including other crops, vegetables, and weeds.  So, make sure they are feeding upon the developing seeds before making treatment decisions.

For more information on management of soybean pests, please refer to the 2018 Soybean Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/mf743.pdf

 

Volunteer Wheat

–By Dr. Jeff Whitworth and Dr. Holly Schwarting

Again, please remember every moisture event prompts the growth of volunteer wheat.  This volunteer wheat needs to be controlled at least 2 weeks prior to planting to help mitigate all wheat pests;  pathogens, mites, and insects.

 

Sorghum Update – ‘Headworms’, Beneficials, and Aphids

–By Dr. Jeff Whitworth and Dr. Holly Schwarting

Sorghum continues to get the attention of many pests and beneficials.  Chinch bug populations are not diminishing even though they are not as noticeable because most are feeding around the base of the plants and behind leaf sheaths on the stalks.  Much late planted, or at least slower developing, sorghum is still vulnerable to these chinch bugs.  Bugs may also move up to the heads as they emerge from the whorl to feed on the forming kernels that provide a succulent source of nutrients.

‘Sorghum headworms’, mostly corn earworms but also a few fall armyworms, are infesting all sorghum fields (not yet in the soft dough stage) that we monitored throughout north central Kansas.  Most fields have close to, or are exceeding, 100% infestation levels (1 or more larvae/head).  These larvae are present in all different sizes, or developmental stages, from 1st to 4th instars.  Thus, they will be feeding on these kernels for at least another 7 – 10 days.

Remember, between flowering and soft dough, these larvae will cause 5% yield loss/ worm/ head.  Very few beneficials are available to help control headworm populations.  However, there are huge populations of beneficials currently present to help control any aphid pests that are, or might be present in the near future.

 

 

Corn leaf aphid populations were common on earlier planted sorghum, and still are on later planted sorghum that is just reaching the whorl stage.  These corn leaf aphids have really helped fuel the beneficial populations.  Fields that have headed out are swarming with lady beetle adults and larvae, syrphid or hover flies, green lacewings, and parasitic wasps.

 

 

 

Sugarcane aphid (SCA) populations are becoming scattered around north central KS, slowly so far, and are really attracting the attention of all these beneficials, which will hopefully help control colony growth.

For management considerations and recommendations for these, and other sorghum pests, please refer to the 2018 Sorghum Insect Management Guide:   https://www.bookstore.ksre.ksu.edu/pubs/mf742.pdf

 

 

New Extension Publications – Pesticides and Bees; Squash Bug and Squash Vine Borer

–by Dr. Raymond Cloyd

Pesticides and Bees

This extension publication is intended to increase awareness of the impact of pesticides on bees and offer suggestions on how to protect bees from pesticide exposure. It describes how bee behavior influences pesticide exposure and toxicity, and why laboratory studies reach different conclusions than what researchers have observed in the field. Benefits and risks associated with specific types of pesticides and application methods are discussed, as well as, complex pesticide interactions, which increase risks to bees but are not well understood. Below is the link to retrieve a PDF file of the extension publication:

 

https://www.bookstore.ksre.ksu.edu/pubs/MF3428.pdf

 

 

Squash Bugs and Squash Vine Borer

Both squash bug and squash vine borer are still creating havoc in vegetable gardens throughout Kansas. What can you do to alleviate the damage caused by these insect pests? Well, there are extension publications on both insect pests that were up-dated in 2016 by Drs. Raymond Cloyd and James Nechols. Below is the link to these extension publications:

 

  1. Squash Bug

 

https://www.bookstore.ksre.ksu.edu/pubs/MF3308.pdf

 

 

  1. Squash Vine Borer

 

https://www.bookstore.ksre.ksu.edu/pubs/MF3309.pdf

 

Soybean Update – Defoliators and Podworms

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Soybeans seem to be attracting the attention of many different types of pests, including many defoliators.  Currently, they are mainly green cloverworms, yellowstriped armyworms, and thistle caterpillars.  Fortunately, populations of these species, or any others for that matter, have not reached densities that have warranted insecticide applications, for the most part.

Unfortunately, soybean podworm (a.k.a. corn earworm/sorghum headworm/cotton bollworm) populations are on the increase in south central and north central Kansas.  These worms eat right through the pod to get at, and consume, the seeds within.  So, as the seeds are filling, they are susceptible to being fed upon by these podworm larvae.  They will feed on smaller, more succulent beans for 10-14 days, then cease feeding to pupate.  Since they are feeding directly on the marketable product, it doesn’t take much of this feeding to reduce yield.

 

 

One important point to remember relative to treating for soybean podworms: these are contact insecticides and thus they must physically contact the targeted pest.  Therefore, you need to utilize enough carrier (water) to penetrate throughout the soybean canopy to get to where these larvae are feeding.  But, you need to do this while the larvae are still small and before they have negatively impacted the yield.  There will probably be at least one more generation this year, so monitoring needs to continue as long as plants are adding pods and there is succulent green reproductive tissue to feed on.  For treatment thresholds and insecticide information, please refer to the 2018 Soybean Insect Management Guide available at: https://www.bookstore.ksre.ksu.edu/pubs/mf743.pdf

 

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