Crop rotation is the most consistent and economical means of controlling western corn rootworm populations. Cultural practices that promote strong root systems and a vigorous crop will make corn more tolerant to rootworm feeding and damage. The number of adult beetles present during the previous growing season is the best guide for selecting the fields that need to be treated with insecticide. Although both species can be found in corn-growing areas across the state, only WCR is considered an economic problem. Life History and Damage The WCR overwinters in the egg stage.
Eggs start to hatch in late spring.
The date depends on soil temperature. Hatch in southern Colorado usually starts in mid-May, while eggs in cooler areas do not hatch until early June. After hatching, the small rootworm larvae move to nearby corn roots and begin feeding on root hairs and small roots. Larger rootworms feed on and tunnel in primary roots. Yield losses due to rootworm feeding are difficult to determine, as many corn varieties can compensate for some root damage.