Crop & Pest Report

Accessibility


| Share

Grasshoppers Emerging (06/13/19)

Grasshoppers are generalists, feeding on grasses, weeds and most field crops.

Grasshoppers are generalists, feeding on grassesent.3, weeds and most field crops. Their life cycle is completed in 40 to 60 days from egg to nymph (young grasshopper) to adult. When a grasshopper first hatches from the egg, the nymph is only about the size of a wheat kernel. Grasshoppers pass through 5 to 6 growth stages as a nymph depending on the species of grasshopper. Nymphs do not have wings, only wing pads (arrow in photo), so they must crawl into fields.

Grasshoppers like hot and dry weather better than cool and wet weather. Cool, wet weather increases disease occurrence and delays development of grasshoppers, reducing the overall population. The current forecast is for below normal temperatures and above average moisture this week, so it is not favorable for grasshopper development.

Farmers and ranchers often use the beginning of bloom in common lilac as an indicator of when grasshopper hatch is under way. Yes, lilacs are blooming and so grasshopper nymphs are emerging. It is too early to say if we will have any problems with grasshoppers moving into field edges or fields. For crop damage, the chewing mouthparts of grasshoppers cause defoliation of leaves, and clipped heads or pods (usually later in season when adults are common).

IPM scouts have found low numbers of grasshopper nymphs last week (see map). Regular scouting of field edges is important because populations vary year to year. Use a 15-inch sweep net to find small grasshopper nymphs in grassy ditches next to emerging field crops. Action thresholds are based on the number of grasshopper nymphs or adults per square yard. Since it is difficult to estimate the number of grasshoppers per square yard when population densities are high, scouts can use four 180-degree sweeps with a 15-inch sweep net to estimate the number of adult (or nymph) grasshoppers per square yard. Early detection of grasshopper nymphs is vital for effective pest management.

 

The action threshold for nymphs is:

  • 50-75 per square yard in field margins
  • 30-45 per square yard within the field

 ent.4

 

 

Janet J. Knodel

Extension Entomologist

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

USDA logo

Creative Commons License
Feel free to use and share this content, but please do so under the conditions of our Creative Commons license and our Rules for Use. Thanks.