Forest Pests: Insects, Diseases & Other Damage Agents

White Slant (Tetracis cachexiata)

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. Brownish gray body with somewhat flattened head, swollen T2, and various, often darkened warts, tubercles, and ridges. Gray and brown head with dark brown marks and with swollen, yellowish clypeus. Thoracic segments (especially T2) with wing-like, subdorsal expansions. Grayish middorsal stripe edged with black and usually dashed until A8; transverse dorsal ridge with paired tubercles on A4, A5, and A8; additional, but smaller, tubercles on dorsum of other segments. Spiracular swelling on most segments; prominent, dark brown subspiracular tubercles before and after spiracle on A1 and A2; prolegs larger on A10 than A8. Up to 40 mm.

Food. Many trees and shrubs, including balsam fir, eastern hemlock, eastern larch, eastern white pine, and white spruce.

Life Cycle. One generation. Pupa usually overwinters in soil or debris. Mature caterpillar present mainly from July to September.

Comments. This species is another twig mimic that becomes rigid after it has been disturbed. Wagner et al. (2001) have suggested that in late summer and early fall the white slant has a partial second generation in some eastern states, but we have not witnessed one. In southern New Jersey, the adults fly during May and June.

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