Grasshopper Management

Grasshoppers are a major pest of both cultivated cropsand rangeland grasses in the world’s semi-arid regions. Areas receiving less than 750 mm of precipitation in the form of rain or snow are particularly susceptible. Traditionally drier areas like southern Alberta are more prone to recurring problems, but serious grasshopper infestations can occur in cropland throughout the province. Although the majority of grasshopper damage has been to cereal grains, other crops can be seriously affected. In a more diversified agricultural landscape where cereal crops are often rotated with other cultivars such as canola, lentil and peas, grasshoppers continue to cause significant economic loss in Alberta. Grasshoppers eat 30 to 100 mg of plant material (dry weight) each day. Forage losses are seldom estimated, but it has been shown that even a moderate infestation of 10 grasshoppers/square metre can typically consume up to 60 per cent of the available forage, depending on the condition of the forage stand. The insects can also consume ALL of the cereal crops, but they usually work the outer edges of fields. The type and extent of crop damage will depend on the type of crop, how well the crop is growing, the number of grasshoppers present, and whether or not adequate cultural and chemical controls are used. Grasshopper description The name “grasshopper ” has been given to a very large and diverse group of insects. All members of the group are characterized by chewing mouth parts, slender bodies, wings that fold lengthwise, large powerful hind legs for jumping and a gradual change in form and size as they develop. Grasshoppers are divided into two major subgroups: the short-horned grasshoppers (Figure 1) and the long-horned grasshoppers, Mormon crickets and katydids (Figure 2). Short-horned grasshoppers are responsible for most of the reported crop losses. As a result, individuals of this subgroup are popularly referred to as “grasshoppers.” Figure 1. A mature two-striped female grasshopper (Melanoplus bivittatus). Note the distinct two stripes running the full length of the body and the single black stripe on the hind leg. Figure 2. The Mormon cricket (Anabrus simplex) is an example of a long-horned grasshopper. The adult male hangs on vegetation and sings loudly. This species can reach high densities in the U.S., but does not normally cause a problem in Canada. Ph ot o: D a