Canadian Forest Service Publications

A sampling system for eggs of western blackheaded budworm, Alceris gloverana (Walsingham) (Lepidoptera: Tortricidae), on western hemlock, Tsuga heterophylla (Raf.) Sarg. 1990. Shepherd, R.F.; Gray, T.G. The Canadian Entomologist 122: 555-562.

Year: 1990

Issued by: Pacific Forestry Centre

Catalog ID: 2979

Language: English

Availability: Order paper copy (free)

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Eggs of western blackheaded budworm, Acleris gloverana (Walsingham), are laid on the lower surface of western hemlock, Tsuga heterophylla (Raf.) Sarg., needles. A comparison was made of the following measures of sample branch size as a basis for expressing egg density: fresh branch weight, branch area, total twig length, branch volume, and number of buds. The criteria for selection of these measures were as follows: correlations of branch size with dry needle weight, variances of egg density and their relative contribution to sample size, and ease of measurement. Fresh branch weight was the best choice. A sequential sampling system was developed on this basis and was related to a scale of predicted defoliation. In addition, a transformation was provided for use in data analysis.