Andricus crystallinus n. sp.

I have received at different times from Mrs. E. H. King, of Napa City, Cala., a singular species of gall which grows in clusters on the leaves of Q. agrifolia? usually but not invariably on the under side. Full grown galls are from .30 in length to .13 in diameter, but only a few seem to reach maturity. Some are mere points. They are often quite dense clusters and remind one of our common A. flocci Walsh, by their woolly appearance, but the bright pinkish wool is resolved by the magnifier into a beautiful mass of brittle crystalline fibres. The largest galls terminate in an elongated neck, the lower half of which is generally smooth, while the upper part branches out tree-like. So far as I can discover these galls contain neither woody fibre nor cellulose tissue. They bear no resemblance to any ordinary vegetable growth ; but the body of the gall and the crystalline frost-work that covers it have a clear, semi-transparency, more or less pinkish, like beautifully tinted glass. The galls have a strong astringent taste, and are nearly pure tannic acid. On opening two mature galls I found two dead but fully matured gall- flies. Each gall contains two chambers, one above the other, with a very thin partition between them. The larva matures in the lower chamber.

This species differs materially from A. echinus O. S., though the galls bear a close resemblance to that species as described by Baron Osten Sacken. The black body of the insect, and the entire absence of clouds or spots in the subhyaline wings seem to separate them specifically.

- HF Bassett: (1900) New Species of North American Cynipidae (1900)^©

Reference: https://www.biodiversitylibrary.org/page/7522373#page/343/mode/1up