none Quantitative information on the life history of the parsnip webworm, D. pastinacella (Duponchel), was gathered from 3 insect populations and their host plants in the Ames, Iowa, area. The eggs are apprx 0.56 mm long and 0.29 mm wide. Both laboratory-reared and field-collected larvae progress through 6 stadia identifiable by head-capsule-width measurements. Developmental time in the laboratory (egg to adult) is apprx 38 days, including 4 days in the egg stage, 21 days in the larval stage and 13 days in the pupal stage. A complete and viable 2nd generation seems unlikely in Iowa. Numbers of both eggs and larvae in the field declined dramatically from the 1st to the 2nd generation and no 2nd-generation pupae were found. Most eggs are laid on parsnip levels; most larvae occur in immature parsnip umbels; most pupae are formed within parnsnip stalks. Parasitoids, primarily Apanteles depressariae Muesebeck (Hymenoptera: Braconidae), were rare and only emerged from 4th-instar hosts. Overwintering seems to occur in the adult stage, but moths were very difficult to collect in the field.