Grasshopper outbreaks are occurring in several areas in Montana. They are difficult to control due to their migratory nature and voracious feeding on several host plants. They tend to avoid feeding on trees and large shrubs unless outbreaks are heavy.

Differential grasshoppers

Figure 1. Differential grasshoppers. Photo by E. Manigault, Clemson Univ., Bugwood.org

Life cycle:

Most grasshoppers overwinter in the egg stage in the soil. After egg hatch in mid- to late spring, the nymphs (immatures) immediately begin feeding. There are at least five or six stages of nymphs before the grasshoppers reach adulthood. The adult grasshoppers can live for

Migratory grasshopper

Figure. 2. Migratory grasshopper, Photo by J. Berger, Bugwood.org

several months into late summer/early fall.

Management:

Once grasshoppers have entered the yard and garden, management is extremely difficult. Additionally, as they get larger, they are more difficult to control.

  • Screen the garden and sensitive areas with metal window-type screening, as they easily chew through fabric.
  • Several insecticides are available and labeled for use on grasshoppers; however, they will have to be applied every few days. Avoid applications of insecticides to any flowering plants or to where pollinators are foraging.
  • Biological controls/baits:

◊   Nosema locustae (brands such as NoLo Bait) http://nolobait.com/nolo-bait/

♦   Nosema locustae is a protozoan/fungus that is selective to grasshoppers and applied with a bran            that the grasshoppers have to consume.

♦   Only effective when grasshoppers are in their 1st and 2nd nymph stages
(when the grasshoppers are 1/4-1/2" long)

                                                                                                                                         MSU Extension Log

By Laurie Kerzicnik (lauren.kerzicnik@montana.edu)

Disclaimer: These recommendations are provided only as a guide. It is always the pesticide applicator’s responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned. The authors and Montana State University assume no liability resulting from the use of these recommendations

Grasshoppers in the Yard & Garden pdf download