Grasshoppers, an Agricultural Pest
July 16, 2025
- Grasshopper swarms can quickly cause considerable damage to agricultural crops.
- Understanding grasshopper life cycles helps with species identification and management timing.
- Effective management strategies include monitoring grasshopper populations, implementing cultural practices, and utilizing integrated pest management (IPM) techniques.
Grasshoppers fill an ecological role as a food source for various predators, including birds and small mammals. However, they can become agricultural pests by feeding on and damaging crops. Grasshoppers may destroy a high percentage of plant foliage without ingesting the tissue.1
Grasshoppers vary in size, color, and markings. Key features for species identification include body length, wing shape, coloration, and patterns. The most common grasshopper species in agricultural crops include the twostriped (Figure 1), redlegged (Figure 2), differential (Figure 3), and migratory (Figure 4).2 The migratory grasshopper is considered the most crop-damaging species in the United States.1 The twostriped species can also be devastating, as 10 adults per square yard in a corn field can defoliate the crop. However, sorghum over six inches tall is less attractive to feeding and nearly immune. A large swarm of differential grasshoppers can destroy a young corn field in three to four days. The differential grasshopper seems to favor wilted or damaged sunflower, possibly because of sugar or amino acid changes in the wilted tissues. The redlegged grasshopper is the most abundant species in the eastern US and Canada.1
Though identifying the specie(s) present may not seem important, identification can be an important factor for management. Identifying different grasshopper species involves a systematic approach that includes observing physical characteristics, utilizing collection methods, and consulting identification resources. Regardless of species, crop feeding injury is similar; however, timing of egg hatch and developmental growth from nymph to adult can vary.
Collection Methods
A sweep net can be used to collect grasshoppers for identification. Start checking for potential infestations at field borders such as grassy fence rows, waterways, and road ditches. These are generally prime areas for egg laying and nymph feeding after hatching. If a net is not available, walking through these areas to observe for hopper activity can provide a reasonable population estimation. The square foot method can also be employed, by which grasshoppers are counted in designated square foot areas to assess population density and diversity.
When the nymphs become larger or the grassy areas are mowed or become dry, the hoppers start moving into nearby crops. Ragged crop leaves are a sign they have moved into the field (Figure 5). In soybean, leaves can be tattered and pods and developing seed can be fed upon (Figure 6).
Grasshopper Life Cycle Stages
Understanding the life cycle of grasshoppers helps with species identification and management timing. High temperatures in the summer and fall allow for a longer season for grasshoppers to lay eggs. In late summer and into fall, and depending on species, the females lay 8 to 30 eggs in the soil and surround them with a liquid that forms a pod. Each female may lay about 100 eggs during the season.2 They prefer to lay eggs in uncultivated, firm soil, such as roadsides, pastures, and field borders. The eggs can overwinter and hatch into small wingless nymphs when the weather warms in May or June. Before becoming adults in about 40 to 60 days, the nymphs pass through five to six growth stages or instars. Heavy rainfall during the hatching phase can cause a high mortality rate among grasshopper nymphs. Extended periods of warm, wet weather promote fungal pathogens that can also reduce overall populations.2
After collection, the images in this article, field guides, and online websites can help with species identification. Consulting entomologists or local agricultural extension services can also aid in identification.
Grasshopper Management
Grasshopper management is essential for protecting crops from potential damage. Effective management strategies include monitoring grasshopper populations, implementing cultural practices, and utilizing integrated pest management (IPM) techniques. Timely field scouting helps confirm grasshopper presence and an estimation of density. Cultural practices such as crop rotation and maintaining healthy soil can disrupt grasshopper life cycles and help reduce populations. When necessary, targeted insecticide applications can be employed to help minimize the impact on beneficial insects. Applications of insecticides to field borders next to egg beds can be a useful tactic as insecticides are applied to a smaller area and smaller nymphs are more susceptible to insecticides. These strategies can help farmers manage grasshopper populations and help to safeguard their crops.
Always read and follow pesticide label directions.
Thresholds for Treatment in Various Crops
Soybean: Consider treatment if eight or more adult grasshoppers per square yard or 15 or more nymphs per square yard are present. Consider an insecticide if more than 5% of the pods are fed upon.3
Corn: Consider treatment when five to eight grasshoppers per square yard are present from just before pollination until anthesis is complete.4
Wheat: Consider treatment if 21 to 40 grasshoppers per square yard are feeding in the field margins or 8 to 14 grasshoppers per square yard are feeding in the field.5
Sources
1Pfadt, R.W. (1994 electronic publication by Schell, S. and Schell, S.) Field guide to common western grasshoppers. Grasshoppers of Wyoming and the west. University of Wyoming, Wyoming Agricultural Experiment Station Bulletin 912. https://www.uwyo.edu/entomology/grasshoppers/field-guide/factsheet.html
2Hein, G.L. and Campbell, J.B. 2008 revision. A guide to grasshopper control in cropland. University of Nebraska-Lincoln, NebGuide. G1627. https://extensionpubs.unl.edu/publication/g1627/2008/html/view
3Dean, A. and Hodgson, E. 2024. Hungry hungry (grass) hoppers. Iowa State University Extension and Outreach, Integrated Crop Management. https://crops.extension.iastate.edu/cropnews/2024/07/hungry-hungry-grass-hoppers
4Zukoff, A., McCornack, B.P., and Whitworth, R.J. 2024. Corn insect pest management 2024. Kansas State University Agricultural Experiment Station and Cooperative Extension Service. https://bookstore.ksre.ksu.edu/pubs/corn-insect-pest-management-2024_MF810.pdf
5Varenhorst, A., Wagner, P., and Rozeboom, P. 2021. Grasshoppers are causing concerns in South Dakota crops. South Dakota State University Extension. https://extension.sdstate.edu/grasshoppers-are-causing-concerns-south-dakota-crops
Additional Resources
Royer, T.A. and Mulder, P.G. 2017. Grasshopper management in rangeland, pastures and crops. Oklahoma State University Cooperative Extension Service. EPP-7196. https://extension.okstate.edu/fact-sheets/grasshopper-management-in-rangeland-pastures-and-crops.html
Bauernfeind, R.J. 2005. Grasshoppers in the lawn and garden. Kansas State University Agricultural Experiment Station and Cooperative Extension Service, Home and Horticultural Pests. L-868. https://bookstore.ksre.ksu.edu/pubs/grasshoppers-in-the-lawn-and-garden-home-and-horticultural-pests_L868.PDF
Web sources verified 7/10/25. 1215_599701