AN ASSESSMENT OF TREE BANDING TECHNIQUES
TO CAPTURE CANKERWORM DEFOLIATORS OF
ELM AND ASH TREES IN WINNIPEG, MANITOBA,
Kerienne R. La France and A. Richard Westwood
Abstract: Fall cankerworm (Alsophila pometaria L.) and spring cankerworm (Paleacrita vernata Peck) are widely distributed across North America. The larvae feed on the leaves of several species of urban street trees, and repeated severe defoliation can cause a reduction in growth and may contribute to tree mortality. This study examined the effectiveness of Tanglefoot-covered tree bands and the Bug Barrier Tree Band in preventing the upward movement of female cankerworms on the trunk by comparing capture rates of adult moths. There were no significant differences among tree species in the number of A. pometaria adults caught, while P. vernata showed a preference for elm (Ulmus spp.) over ash (Fraxinus spp.). Up to 25% of female moths crossed the Bug Barrier Tree Band, and up to 20% of females crossed the Tanglefoot-covered bands in three experiments in 2002 and 2003. There was no significant difference between the two band types in the proportion of females crossing bands. Larval populations were not large enough to determine the effect of the bands on reducing tree defoliation. The Bug Barrier Tree Band was easier to install and remove than the Tanglefoot-covered bands and required considerably less clean-up afterward.
Keywords: Alsophila pometaria; defoliation; Paleacrita vernata; tanglefoot bands