Technical Abstract: Few studies have examined fire effects on grasshopper species. Our previous work suggests selective control of some pest grasshoppers with prescribed fire. We tested whether selective control was due to heat damage to eggs that differ by species because of egg laying depth. Deep- (migratory) and shallow-egg laying (white-whiskered) grasshopper species were selected to lay eggs in soil cores. Soil was exposed to a range of heat intensities and proportion of eggs hatched was determined. Proportion of eggs hatched was not affected by heat intensity in the deep-laying migratory grasshopper, but was sharply reduced to near zero for the white-whiskered grasshopper. This is the first study linking field observations of grasshopper populations after fire to the specific mechanisms responsible. Prescribed fire shows promise as a selective control agent for pest grasshoppers.