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Extension Entomology

Month: September 2018

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

 

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