The effects of maize (Zea mays L.) phenology on establishment and adult emergence of the western corn rootworm (Diabrotica virgifera virgifera LeConte) and plant damage to maize was evaluated in field trials in 2001 and 2002 and in the greenhouse. Although neonate western corn rootworm larvae were able to initially establish on maize roots during anthesis and early reproductive stages, these older roots were apparently unsuitable for complete western corn rootworm larval development. The number of western corn rootworm beetles that emerged from eggs that hatched during anthesis to early reproductive stages was significantly fewer than the number of beetles that eclosed from V4 to V11. Plant damage was also lowest from larvae that eclosed during anthesis to early reproductive stages. Potential causal mechanisms and implications of these data in terms of potential management strategies in the future are discussed.