Grasshoppers

Grasshoppers

The four main pest species of grasshopper in Nebraska. Top row (left to right) two striped grasshopper adult, red legged grasshopper adult. Bottom row (left to right) differential grasshopper adult, migratory grasshopper adult. Photos courtesy of UNL Insect Identification Laboratory.
The four main pest species of grasshopper in Neb. Top row two striped grasshopper adult, red legged grasshopper adult. Bottom row differential grasshopper adult, migratory grasshopper adult.

You may remember grasshoppers from Aesop’s fables as sort of shiftless, lazy creatures that played music and depended on the kindness of ants to get them through the winter. Unfortunately, not only do grasshoppers work hard on their music, they also work really hard to eat all of your garden plants. Certain years hold more grasshoppers than others and it seems like 2016 has been kind to the jumping pests.

Grasshoppers will begin moving into yards and gardens around the middle of July and continue to do so until the end of August. At this point the insects will begin feeding on the flowers and leaves of many different types of plants including beans, corn, and lettuce. Sometimes they get so hungry they will eat anything, even paint, window screen, and the handles to tools.

Grasshopper females egg “pods” in the upper layers of bare, untilled soil areas. Grasshoppers through a type of development that we call incomplete metamorphosis, meaning that when they hatch they look like tiny grasshoppers and slowly feed and molt into adult grasshoppers with wings. This is the opposite of complete metamorphosis (egg, larvae, pupa, and adult) that we see with butterflies, beetles, etc. When grasshoppers are young they typically feed on the same things they would as an adult.

In normal years you can rely on natural predators to keep grasshoppers in check. Since they produce so many eggs and so many tiny grasshoppers, lots of predators use grasshoppers as a food source. Blister beetle grubs will hunt and consume grasshopper egg pods, while robber flies, spiders, and birds gobble up adults. Grasshoppers are also susceptible to parasites like nematodes.  

Unfortunately, there are times when natural enemies can’t keep up with the grasshopper populations and this leads to local outbreaks like we have this year. Adults are large and in charge and therefore can be difficult to control with insecticides. If you can apply liquid insecticides during the 3rd or 4th instar of the grasshopper’s life (usually in July) you will achieve maximum insecticide control. A liquid broadcast spray over the garden of carbaryl, bifnethrin cyfluthrin, or lambda cyhalothrin would all work against these hungry, hungry insects. If you are looking for a more targeted approach to control, consider the use of an insecticide treated bait. These would be wheat bran flakes treated with carbaryl insecticide and also provide excellent control. Other, more integrated approaches to grasshopper reduction and control include dense plantings of turf in areas of bare soil or tilling bare areas to eliminate egg laying sites. You could also consider a trap crop area of zinnias or other lush vegetation that will attract and hold migrating grasshoppers. Then you can treat those areas instead of your garden.

 

For more info go to: http://www.ianrpubs.unl.edu/epublic/live/g1633/build/g1633.pdfOr google NEBGuide G1633

Jonathan Larson

Dr. Jonathan L. Larson, Nebraska Extension, provides a monthly feature on pests that may be a problem in your home or on your acreage. This month he is featuring How to Deal with Pesky Grasshoppers.