Sorry I couldn't get more magnification on this. When I found it (lots of them on fallen leaf undersides from a Quercus agrifolia) the white stuff was more pronounced, but had dessicated by the time I took the shot. They look like little black legless trilobites, and seem to have attachment traces if you knock them off - a very few including what looks like a drilled penetration into the leaf beneath. Almost a pupal appearance, but it would seem unlikely to have such a mass of pupae altogether in the same place. Of course that would put them out of Homoptera. Most have exit holes, presumably from some parasitoid, guessing wasp. At first thought white stuff was fungi colonizing the corpses, but think it more likely remnant waxy stuff from the insects themselves. Brief examination of lower branches shows no obvious candidates for living insects, but I'll try to get farther up the tree.

Any ideas anyone?

Terrel Brand