Sawfly
Symphyta
16 host plants
Yellow-green sawfly larvae with black spots and black head capsules feed on birch leaves in Western Washington, with early instars consuming interveinal tissue and late instars consuming entire leaves. When disturbed, larvae form their bodies into an S-shape. Dusky birch sawfly larvae can reach up to 1 inch length and feed in groups around leaf margins.
Distinguish sawflies from caterpillars: sawflies have 6 or more abdominal prolegs. Monitor May through July for feeding. Heavy infestations cause defoliation, but established trees tolerate damage. Prune infested branches if desired. Chemical control rarely needed on healthy birches.
Host Plants (16)
Betula alleghaniensis Yellow Birch
Betula davurica Asian Black Birch, Dahurian Birch
Betula glandulosa Dwarf Birch Bog Birch, Scrub Birch
Betula lenta Sweet Birch, Cherry Birch, Black Birch
Betula maximowicziana Monarch Birch
Betula nana Dwarf Birch, Bog Birch
Betula nigra River Birch, Black Birch
Betula occidentalis Water Birch, Western Birch, Red Birch, River Birch, Black Birch
Betula papyrifera Paper Birch
Betula pendula European White Birch
Betula platyphylla Asian White Birch, Manchurian Birch
Betula populifolia Gray Birch, Fire Birch
Betula pubescens Downy Birch, Moor Birch
Betula utilis Himalayan Birch, Bhojpatra, Indian Paper Birch
Betula utilis subsp. albosinensis Chinese Paper Birch, Chinese Red Birch
Betula utilis subsp. jacquemontii Whitebarked Himalayan Birch