How to Manage Pests
UC Pest Management Guidelines
Grasshoppers are readily distinguished from most other insects by hind legs, that have greatly enlarged femurs, 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.
Grasshoppers feed on leaves and stems. When populations are high they can cause severe defoliation.
Economically significant levels vary with the growth of the crop; in general, populations of 15 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.
UC IPM Pest Management Guidelines: Alfalfa