. Agricultural plant pest control : a study manual for commercial and governmental pesticide applicators . Weeds; Pests. vae to the surface. Late evening applications are most effective when they are beginning to feed. Weed control is important along field edges. Cutworms move from edges to the field as weeds dry up. Grasslwvjie Life cycle: There are over 100 species of grasshoppers in Montana, but only a few ever reach economically important levels. These in- clude the migratory grasshopper, twostriped grasshopper, redlegged grasshopper, clearwinged grasshopper and the bigheaded grasshopper T
. Agricultural plant pest control : a study manual for commercial and governmental pesticide applicators . Weeds; Pests. vae to the surface. Late evening applications are most effective when they are beginning to feed. Weed control is important along field edges. Cutworms move from edges to the field as weeds dry up. Grasslwvjie Life cycle: There are over 100 species of grasshoppers in Montana, but only a few ever reach economically important levels. These in- clude the migratory grasshopper, twostriped grasshopper, redlegged grasshopper, clearwinged grasshopper and the bigheaded grasshopper These species overwinter in the egg stage in the soil. The eggs are laid in pods in the soil during late summer and fall and the nymphs begin emerging in April, May, and June. Nymphs feed on vegetation for 40 to 60 days before molting into the adult stage. Adults dis- perse to suitable hosts during the summer and lay the overwintering eggs. Some species have well defined breeding and egg laying areas. In most areas, eggs are laid in waste areas, along roadsides, and around field Adult grasshopper Damage: Damage to crops occur when hop- pers migrate from rangeland adjacent to fields as the vegetation drys. The green crops are a very appealing site to these hoppers. Grasshop- per adults and nymphs cause defoliation as they feed. They will feed on all of the above ground parts of a plant. In large numbers grasshoppers can totally eat whole fields of crops. Habitat: Grasshoppers are found in range- lands, roadsides, and croplands. Control: Temperature and moisture are im- portant factors in reducing grasshopper popula- tions. Heavy mortality occurs in the spring when warm weather causes premature hatching of eggs. In late spring, short periods of hot weather increases the incidence of fungus (Entomophaga grylli. Figure 1) and bacterial diseases. Grass- hopper control should be initiated when the population reaches about 10 per square yard and are in the nymphal stage (see
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