Due to a tip from a friend, Craig Sondergaard and I went lace bug hunting at Powell Butte in Portland, Oregon after work one evening last month. And, lo and behold, we actually found the bugs we sought within minutes of leaving the van. The first clump of Oemleria cerasiformis (osoberry) we encountered had little white spots (called chlorotic spots because they’ve been drained of chlorophyll) on the top of some leaves, and Corythucha salicata (as confirmed by both Alexander Knudson and Dr. Laura Miller) on the underside!
Unfortunately we didn’t find any nymphs so we can’t claim to have positively found a new host plant for this species. But it seems likely that this is a host plant, since almost every osoberry we found had one to several of these Corythuca salicata (they are often incorrectly called willow lace bugs but that common name has been usurped by the Canadian lace bug Corythucha elegans) busily feeding on the leaves.
As beautiful as they are, and despite being a native, they can be a real pest in apple orchards. It seems that, despite having undoubtedly evolved to eat willows and other native vegetation, they actually prefer to eat apple leaves, and will choose apples over willows as larval hosts, even when both are present. And they can do some real damage if their population is large enough. Wong (1933) found over 200 of them on a single apple bud in an untreated orchard.
Description-Small (3.5mm x 2mm), mostly cream to white, with brownish bands along the wing base and near the apex, a brown spot near the margin, and brown humps in the middle of the elytra; hood somewhat less than twice the height of the median carina, and lateral carina ending well short of the hood; small and relatively few spines on paranota and elytra.
Similar species-High magnification, a key, and probably expert assistance are required for any positive identification in this genus, and the plant they were found on, as well as those nearby, is very useful information; C. pergandei, C. cerasi, C. occidentalis, C. distincta, and C. morrilli all have hood that is more than twice as high as median carina; C. immaculata are all white.
Habitat-Wherever there are host plants; since they use willow, wetlands and riparian corridors are probably their ancestral habitat.
Range-Western North America; probably region wide in appropriate habitat.
Eats-The primary larval hosts are various willows, but they also utilize apple, cherry, and other members of the family Rosaceae. Adults are less picky and suck the sap from many different species of leaves.
Eaten by-They are gleaned by insectivorous birds, and lacewings, jumping spiders, lady beetles, and parasitic wasps attack most Corythucha species.
Reproduction-Eggs are deposited singly along the veins on the underside of the leaf; eggs are inserted a little over halfway into the leaf, in an opening cut by the serrated ovipositor, and are then obscured by a dark substance secreted by the mother; eggs take about 3 weeks to hatch.
Adults active-Overwintering adults probably come out of diapause in March and last through June, depending on weather; then adults are active from June through September after emerging from the larval phase; overwinter under cover as an adult in diapause, usually starting by the first week of October
Etymology of names–Corythucha translates from the Greek as ‘helmet bearer’, and references the helmet like ‘hood’ that covers the head. The specific epithet salicata is from the Latin for ‘willows’, and comes from the fact that Salix spp. (willows) are a primary larval host.