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Extension Entomology

Author: Sharon Schroll

Grasshoppers

— by Dr. Jeff Whitworth and Dr. Holly Davis

Just started finding very small, recently hatched grasshopper nymphs.  If, or when, these nymphs start to increase in numbers in the next few weeks, remember the best time to manage them is while they are still small and thus, less mobile.  An application of an insecticide labeled for grasshopper control is most effective, cheaper, and less environmentally disruptive if applied early so it can be better targeted in a smaller area at the most susceptible time to control these pests.

Alfalfa Update – Alfalfa Weevils, Pea Aphids, Etc.

— by Dr. Jeff Whitworth and Dr. Holly Davis

Alfalfa weevil activity has slowed considerably but has not stopped yet.  Fields that have not been treated at all this season still have relatively large populations of larvae, of all sizes, and increasing numbers of adults.

 

Small larvae along with later, more mature instars, plus pupae and newly emerging adults are still developing because of the recent cooler weather which has slowed down weevil development.  The field shown here withstood a weevil infestation feeding on the leaf tissue since early April but is starting to come back with some regrowth as the larval population matures into pupae, then adults. However, the 1st cutting, at least, has been donated to the alfalfa weevil.  In contrast, fields treated in a timely manner are now being, or are ready to be, swathed as soon as possible.

 

Pea aphid populations are starting to increase in fields treated earlier for alfalfa weevils.  However, this is also allowing beneficials to build up which should be helpful for controlling other aphid populations in other crops throughout the growing season.

 

Another example of alfalfa being a great “sink” for other insects – it is the main habitat for adult bean leaf beetles where they hang out until soybeans start germinating.  They will then migrate from alfalfa to feed on seedling soybeans and begin ovipositing around the base of these seedlings.

Bean leaf beetles are often confused with southern corn rootworms which can also be very common in soybeans but do not have the potential to negatively impact yield.  For more information on alfalfa pest management and/or soybean pest management, please refer to the KSU Insect Management Guides.

KSU Alfalfa Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF809.pdf

KSU Soybean Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF743.pdf

Termites

— by Dr. Jeff Whitworth and Dr. Holly Davis

The last few days of warm, sunny conditions after the preceding few days of cooler, wet weather have apparently initiated considerable termite swarming activity.

Again, make sure to positively identify the insects swarming, as ants are also actively swarming.  There is a huge difference in damage potential between termites and ants, even carpenter ants.  So, please refer to these KSU extension publications to properly identify and manage ants and termites:

 

Termites, MF722: https://www.bookstore.ksre.ksu.edu/pubs/MF722.pdf

Ants, MF2887: https://www.bookstore.ksre.ksu.edu/pubs/MF2887.pdf

Biting Gnats

–by Dr. Jeff Whitworth and Dr. Holly Davis

We have received a few calls about “biting gnats”.  These are most likely small black flies, commonly called black flies or buffalo gnats.  These appear every year, usually near moving water, and they can be very persistent at getting a blood meal, which the females require in order to produce viable eggs.  While they can be aggressive biters for 7-10 days, they do not transmit pathogens.  Management is difficult because the females deposit their eggs in slow moving creeks and streams.  Larval populations typically decline considerably once water temperatures reach 75-80°F.

 

For more information, please refer to Household Pests of Kansas (page 65): https://www.bookstore.ksre.ksu.edu/pubs/MF3291.pdf

 

Wheat Aphids and Mites

–by Dr. Jeff Whitworth and Dr. Holly Davis

 

Most wheat fields we sampled around north central Kansas between 2-6 May had populations of bird cherry-oat aphids which were relatively easy to find.  They were in 100% of the sampled areas, however, not on 100% of the plants within those areas.  They are relatively easy to see, because of their dark color, if you examine the lower portion of the plants.  There are no symptoms or signs of their feeding nor would we expect there to be any because of the good growing conditions so far.  The populations are not yet at the density to warrant any concern.

Some winter grain mites were also noted but are nothing to worry about.  Winter grain mites are usually in their summer aestivation, or dormancy, period by now as they prefer cool, cloudy weather.  Thus, they will not be a problem moving forward into this growing season but the fact that there are still a few around is indicative of the cloudy, cool conditions we have experienced thus far this spring.

 

 

It is still NOT recommended to add an insecticide to a fungicide application just to save application costs and to kill the few aphids that are present.  This will do much more harm than good in the long run.  For more information relative to wheat pest and their management, please see the Wheat Insect Management Guide available here: https://www.bookstore.ksre.ksu.edu/pubs/mf745.pdf

 

Revised Extension Publications

–by Jeff Whitworth and Holly Davis

 

Blister Beetles in Kansas, MF959, originally published by Robert Bauernfeind, Randall Higgins, Sue Blodgett, and Lowell Breeden in 1990 has been revised by Holly Davis and Jeff Whitworth. It is now available at: https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=573&pubId=1549

 

Corn Rootworm Management in Kansas Field Corn, MF845, originally published by Randall Higgins, Gerald E. Wilde, and Timothy Gibb in 1995 has been revised by Holly Davis and Jeff Whitworth.  It is now available at: https://www.bookstore.ksre.ksu.edu/Item.aspx?catId=221&pubId=1502

Wheat Aphids

–by Jeff Whitworth and Holly Davis

We are getting calls relative to wheat aphids in many fields throughout south central and north central Kansas.  So far they are mainly bird cherry-oat aphids but a few greenbugs as well.  This is normal for this time of year.  These aphids migrate in, or are blown in, all spring on southern winds.  However, at this time of year/ this stage of wheat development, there is little to worry about relative to aphid feeding.  Also, the weather has been conducive to wheat growth so any aphid population buildup should not significantly impact the wheat.  Any viruses aphids may vector should not impact the wheat at this developmental stage enough to significantly reduce yields.  Aphid populations now will provide a food source and thus help many beneficial insect populations establish for later season aphid invasions.

It is not a good practice to mix a little insecticide in with a fungicide treatment “just in case”, as this is deadly to beneficial insects, i.e. lady beetles, lacewings, etc.  that will provide help later in the growing season on other crops.  Yes, it does save on the cost of an insecticide application but will probably do much more harm than good at this time of year.  For more information on wheat insect management, please refer to the KSU Wheat Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/mf745.pdf

Alfalfa Weevil Update

–by Jeff Whitworth and Holly Davis

This week’s cool, wet weather has kept many growers and applicators out of alfalfa fields.  The cooler weather has slowed down alfalfa weevil activity – but not by much.  Remember, they feed 24/7 as long as the ambient temperature, where they are feeding, is over 48°F. Thus, field monitoring needs to continue until most larvae have pupated or fields are swathed, as weather allows.

If insecticide applications are chosen please remember to consult the label for the pre-harvest interval (PHI) of the insecticide selected.  For more information relative to alfalfa weevil management, please refer to the KSU Alfalfa Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF809.pdf

 

How to Avoid Getting “Bored” by the Ash/Lilac Borer

–by Raymond Cloyd

 

Now is the time to take “action” to prevent damage from the ash/lilac borer (Podosesia syringae). Ash/lilac borer adults are typically active from late-April through June, although activity is contingent on temperature. Adults are brown, clearwing moths that look-like paper wasps (Figure 1). Adult females lay tan, oval-shaped eggs in cracks and crevices, or wounds at the base of plant stems. One female can live for approximately one week and lay up to 400 eggs. Below are nine points associated with the life history and management of ash/lilac borer:

 

Fig 1. AshLilac Borer Adult (Author–City of Edmonton)

  1. The larvae are responsible for causing plant damage by tunneling and feeding within the bark (cambium). Larvae can also tunnel further into the wood and feed within the sapwood and heartwood.
  2. Larval feeding restricts the flow of water and nutrients; thus resulting in shoot or branch dieback. Ash/lilac borer larvae feed at the base of plant stems causing swollen areas or cracks, and they also feed where major branches attach to the trunk.

 

  1. The presence of light-colored sawdust (frass) accumulating at the base of infected trees or shrubs (Figure 2) is evidence of larval feeding.

Fig 2. Sawdust Located At The Base Of An Infected Tree (Auth–Raymond Cloyd, KS)

  1. Ash/lilac borer overwinters as a late-instar larva located in feeding tunnels or galleries.

5. Trees or shrubs infested with ash/lilac borers will have brown papery pupal cases protruding from the bark (Figure 3), which is where adults emerge from.

Fig 3. Pupal Cases of AshLilac Borer Protruding From Tree Trunk (Auth–Raymond Cloyd, KSU)

 

  1. There is generally one generation per year in Kansas.

 

  1. The primary means of avoiding problems with ash/lilac borer is to avoid ‘plant stress’ by providing proper cultural practices including; irrigation (watering), fertilization, pruning, and mulching. In general, stressed plants are more susceptible to attack by ash/lilac borer than ‘healthy plants.’ A two to three foot wide mulched area around the base of trees and shrubs prevents injury from lawn mowers and weed-trimmers that can girdle trees and shrubs leading to ‘stress.’ Moreover, avoid pruning plants in late spring through early summer (under usual weather conditions) as this is when adults are typically present and the volatiles emitted from pruning cuts may attract adult females.

 

  1. Insecticides containing the active ingredients, permethrin, bifenthrin, or chlorantraniliprole can be applied to the bark—at least up to six feet from the base—to prevent ash/lilac borer larvae from entering which exposes them to insecticide sprays. Once larvae are inside the plant, they are not susceptible to insecticide sprays. Systemic insecticides applied to the soil or injected into trees or shrubs do not provide reliable control of the ash/lilac borer.

 

  1. Commercially available pheromone traps capture adult males, which help estimate when females will be laying eggs. Pheromone traps help appropriately time insecticide applications. Insecticide spray applications should begin seven to 10 days after capturing the first adults. Check pheromone traps two to three times per week for the presence of newly captured adult males.

 

Pesticide Recordkeeping Survey

–by Frannie Miller

 

Private applicators are required to keep records of their restricted use pesticide (RUP) applications. The classification of several commonly used herbicides to restricted use means more private applicators are in need of an improved mechanism to keep these records. The Kansas State Pesticide Safety program is trying to collect some data on what producers are wanting/needing to be able to keep more accurate, efficient records.  The program has developed a short survey consisting of 7 questions and wants to obtain feedback from across the state.  The purpose of this survey is to gather your perceptions related to the use of pesticide recordkeeping books/apps and what you would most likely use.  The information you provide will aid us in determining the need for and content of a newly developed pesticide recordkeeping book to assist in tracking pesticide application/use.

Please go to: https://kstate.qualtrics.com/jfe/form/SV_86r84ilD5huDIUZ to complete the survey and give us your feedback.

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