This summer I was working in red maple swamps all over Massachusetts, and it seemed like the underside of every arrow-wood leaf (Viburnum dentatum
) had these white curly fluffy things. The linked image shows the underside of one--it seems totally featureless, so I'm ruling out psyllids, and I guess that leaves whiteflies and scales as options? I'm not sure if any scales actually do something like this. The closest thing I've found is crown whitefly, but those are southern and feed on oak and chestnut.
View of the underside of a different individual:
Update, 9/19/09: I collected some of these a couple of weeks ago, and this morning I looked in the vial and found adult whiteflies had emerged.