How to Manage Pests

UC Pest Management Guidelines

Alfalfa

Grasshoppers

Scientific Names: Melanoplus spp., Trimerotropis spp.

(Reviewed 1/17, updated 1/17)

In this Guideline:


Description of the Pests

Grasshoppers are readily distinguished from most other insects by their hind legs, which have greatly enlarged femurs that are well adapted for jumping. Their bodies are robust and their antennae relatively short. In contrast, another alfalfa pest in the order Orthoptera, crickets, have long antennae. Most grasshoppers are winged and many are good flyers, although a few species are flightless.

Grasshoppers may be a pest in alfalfa production, but vary greatly in importance from area to area and season to season. They sometimes develop in uncultivated areas and move into cultivated fields. They should be controlled before they enter the alfalfa field.

Damage

Grasshoppers feed on leaves and stems. When numbers are high they can cause severe defoliation.

Management

Economically significant levels vary with the growth of the crop; in general, 15 grasshoppers per square yard or higher are considered severe. Control measures will depend on the growth of the crop and the stage of development of grasshoppers present. Grasshoppers are best controlled before they enter alfalfa fields. Check with your county agricultural commissioner regarding the current registration of baits to control grasshoppers in alfalfa fields.

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Alfalfa
UC ANR Publication 3430

Insects and Mites

L. D. Godfrey, Entomology, UC Davis
E. T. Natwick, UC Cooperative Extension, Imperial County
P. B. Goodell, Entomology, Kearney Agricultural Center, Parlier
R. F. Long, UC Cooperative Extension, Yolo County
V. M. Barlow, UC Cooperative Extension, Riverside County and UC IPM Program

Acknowledgment for contributions to Insects and Mites:
D. R. Haviland, UC Cooperative Extension, Kern County
M. Rethwisch, UC Cooperative Extension, Riverside County (Blythe)
C. G. Summers, Entomology, Kearney Agricultural Center

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