Forest Pests: Insects, Diseases & Other Damage Agents

Spruce Bud Moth (Zeiraphera canadensis)

Maier, C.T., C.R. Lemmon, J.M. Fengler, D.F. Schweitzer, and R.C. Reardon. 2004. Caterpillars on the Foliage of Conifers in the Northeastern United States. FHTET-2004-1. Morgantown, WV: USDA Forest Service, Forest Health Technology Enterprise Team; 151 p.

Description. Plump, very light grayish brown body with orange-brown head and prothoracic shield. Head with horizontal dark brown spots or bar behind stemmata; pair of small, offset, gray or brown subdorsal spots on most segments; other small, dark spots near spiracles. Prolegs on A3 to A6 slightly reduced in size. Up to 10 mm.

Food. White spruce, especially in exposed areas; uncommonly other spruces and balsam fir.

Life Cycle. One generation. Egg overwinters near base of shoot with new growth. Mature caterpillar present from May to July.

Comments. The caterpillar typically ties the brownish spruce bud cap to the developing shoot with silk, preventing its drop (see below), and it eats the developing foliage beneath the cap. Afterward, it may move down the developing shoot to eat other new needles. After it finishes its feeding, the caterpillar descends to the ground where it changes to a pupa in the litter. At times, this bud moth can be a serious pest in plantations of white spruce.

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