Outbreaks tend to occur after several successive years of conditions favourable for survival and fecundity. They considered the effects of weather conditions and food quality on development and survival of the eggs, nymphs and adult grasshoppers. Populations tended to decline in areas of above-average rainfall. Winter soil temperatures affect the mortality of grasshopper eggs. Soil temperature has an effect on egg hatching.
Soil moisture affects egg hatch.
Hot, dry weather causes the grasshoppers to move quickly through their 5 nymphal instars, resulting in high adult populations early in the season. Cool, wet weather causes a late and erratic hatch which may extend into late-June. Slow, erratic nymphal development results in low adult populations late in the summer. Given optimum conditions, most grasshoppers will mature in about 30-40 days. Cold weather or prolonged damp spells may slow development.