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Life History and Habits of a Midge, Phytophaga thujae Hedlin (Diptera: Cecidomyiidae) in Western Red Cedar Cones1

Published online by Cambridge University Press:  31 May 2012

A. F. Hedlin
A. F. Hedlin
Affiliation:
Forest Entomology and Pathology Laboratory, Victoria, B.C.
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Abstract

The midge, Phytophaga thujae Hedlin, is a common pest in cones of western red cedar, Thuja plicata Donn. In some years nearly 100% of cones in localities on Vancouver Island, British Columbia, are infested.

Adults emerge in March and April to oviposit on young cones. Eggs hatch during April and May. Larvae feed on seeds and scales, and in late summer spin cocoons in the cones, in which to overwinter. Prepupal and pupal development occur during winter.

Mortality factors include parasites and competition. Species of Torymus and Tetrastichus parasitize larvae of the midge. In years of severe infestation, competition in early stages can cause considerable mortality.

A portion of the population may remain in diapause in the larval stage each year.

Type
Articles
Information
The Canadian Entomologist , Volume 96 , Issue 7 , July 1964 , pp. 950 - 957
Copyright
Copyright © Entomological Society of Canada 1964

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References

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