Factors Affecting the Survival of Larval and Pupal Stages of the Bagworm, Thyridopteryx Ephemeraeformis (Lepidoptera: Psychidae)

Several populations of the bagworm, Thyridopteryx ephemeraeformis (Haworth), were studied to determine the factors affecting survival of the larvae and pupae. Infestations were on Juniperus virginiana (juniper) and Thuja occidentalis (arborvitae). A normal complement of parasites, hyperparasites, and scavengers was recovered with four new records. The ichneumonid Itoplectis conquisitor (Say) accounted for most of the parasitism (75.9%). Females of this species were more often found in female hosts and males in male hosts. Although predation or larvae vacating bags were not directly observed, empty bags were found in each larval population beginning in mid-July and early August. The proportion of empty bags increased sharply from less than 10% to about 50% during a 3-week period but remained at this level for the rest of the season, suggesting that the bags were emptied during the first 3 weeks they were observed.