Sampling western spruce budworm by counting larvae on lower crown branches.

R.R. Mason; B.E. Wickman; H.G. Paul

doi:10.2737/PNW-RN-486

Treesearch

Sampling western spruce budworm by counting larvae on lower crown branches.

Informally Refereed

Authors:

R.R. Mason, B.E. Wickman, H.G. Paul

Year:

1989

Type:

Research Note

Station:

Pacific Northwest Research Station

DOI:

https://doi.org/10.2737/PNW-RN-486

Source:

Res. Note PNW-RN-486. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 8 p

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Abstract

A technique is described for sampling spruce budworm larvae after bud flush by nondestructively beating branches in the lower crown. Sample data were collected from 32 plots representing a wide range of budworm densities. Statistical analyses indicated that larvae were less aggregated in the lower crown than at the same density in the middle crown. In an independent sample of 12 plots, estimates of larval density in the middle crown were 2.5 times higher than but strongly correlated with estimates of density in the lower crown. Sampling in the lower crown is quick and efficient and especially recommended for the annual monitoring of larvae or for estimating densities before spraying in control programs.

Keywords

Sampling insects, insect defoliators, western spruce budworm, Choristoneura occidentalis

Citation

Mason, R.R.; Wickman, B.E.; Paul, H.G. 1989. Sampling western spruce budworm by counting larvae on lower crown branches. Res. Note PNW-RN-486. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 8 p