Within-Crown distributor of male and female bagworm (lepidoptera: Psychidae) pupae on juniper as affected by host defoliation

David L. Cox, Daniel A. Potter

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We examined the within-crown distributions of male and female bagworm, Thyridop–teryx ephemeraeformis (Haworth), pupae on Juniper us virginiana L. as a function of prior defoliation. This was to evaluate the hypothesis that the differential movement of females to the upper crown before pupation would be strongest on heavily defoliated trees. Differential stratification of the sexes occurred irrespective of degree of defoliation, and despite the fact that competition, as evidenced by higher mortality of pupae and reduced weight of egg masses, was apparently greatest at the top of moderately and severely defoliated hosts. There was no relationship between height of pupation and risk of parasitism for either sex. Female larvae were ca. 4-fold more likely than males to abandon a low-lying host upon which they had fed and to ascend the trunks of nearby trees before pupating. Enhancement of larval dispersal by females is the most plausible explanation for the stratified distribution of bagworm pupae within trees.

Original languageEnglish
Pages (from-to)559-567
Number of pages9
JournalThe Canadian Entomologist
Issue number6
StatePublished - Jun 1988

Bibliographical note

Funding Information:
We are grateful to F.C. Gordon, C. Redmond, and D. Ball for technical assistance, and to A.E. Cameron, P.H. Freytag , Y. Pelletier, R.A. Scheibner, and K.V. Yeargan for critically reviewing an earlier draft of the manuscript. K. Barker and S. Lowry provided statistical consultation. This research was supported in part by a grant from the International Society of Arboriculture.

ASJC Scopus subject areas

  • Structural Biology
  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Molecular Biology
  • Insect Science


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