Western webspinning sawfly
16 host plants
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Western webspinning sawfly larvae feed gregariously within loose, grayish webbing on spruce branch tips and branch crotches. Foliage inside the web browns and becomes skeletonized as larvae feed. Picea species show damage from June through August in western Washington. The sawfly creates noticeable aesthetic damage on landscape spruce but rarely threatens tree survival.
Prune branch tips with webbing and larvae intact before adult emergence in late summer. This pruning also improves tree form and removes visual damage. Do not apply pesticides into the webs; parasitoid wasps and predatory insects naturally suppress the sawfly. Trees recover rapidly the following season even after significant defoliation.
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Host Plants
16
Host Plants (16)
Picea abies Norway Spruce Picea abies var. pendula Weeping Norway Spruce, Pendulous Norway Spruce Picea asperata Dragon Spruce Picea breweriana Brewer Spruce, Brewer's Weeping Spruce Picea engelmannii Engelmann Spruce Picea gemmata Szechwan Spruce Picea glauca White Spruce, Canadian Spruce, Skunk Spruce Picea koyamae Koyama's Spruce, Yatsugatake-tohi [Japanese] Picea mariana Black Spruce, Bog Spruce, Swamp Spruce Picea omorika Serbian Spruce Picea orientalis Caucasian Spruce, Oriental Spruce Picea pungens Colorado Spruce Picea pungens var. glauca Colorado Blue Spruce Picea rubens Red Spruce Picea sitchensis Sitka Spruce Picea wilsonii Wilson's Spruce