Last year we saw large populations of grasshoppers in El Paso County and across Colorado. While we might hope this year will be different, the grasshoppers will be back in some way. Why is this?
The grasshopper life cycle can help explain why recent high grasshopper populations are so difficult to manage. Grasshopper embryos begin to develop within eggs immediately after they are deposited by adults and reach a certain stage of development before entering a period of dormancy in the winter, referred to as diapause. Warm autumn weather facilitates that development. Autumn was one of the 10 hottest autumns on record in El Paso County, and December was warmer than usual.
In winter, grasshopper eggs are insulated by snow and vegetation in the upper layer of the soil. In spring, more heat units are needed to complete development. Eggs hatch and the nymphs emerge, looking like very tiny grasshoppers. They molt several times in a process of incomplete metamorphosis before reaching their final adult size. After a cold start to the year, March in El Paso County was one of the 10 hottest on record and April has been quite warm. The embryos had ideal growing conditions and are hatching…