Caryomyia urnula Gagne, new species

Hosts: Carya illinoinensis, tomentosa, glabra, cordiformis, ovata, pallida

Gall (Figs. 28, 41-42): Late spring, early summer, common on the Eucarya section, rare on Apocarya section; found singly between veins on either upper or lower leaf surface; 2.0-3.0 mm in height, cylindrical, slightly bulging at midlength, narrowed abruptly apically to convex areola surrounding prominent nipple, surface smooth to weakly lined longitudinally; hairless, not sticky, white to green, turning dark green or brown; base shallowly concave; wall firm, brittle, uniformly thin, larval chamber glabrous with longitudinal ridges. This gall resembles that of C. cilidolium and relatives in the caplike apex and the central indentation of the base, but it is smaller, and more cylindrical than spheroid. The apex does not break off easily as it does in galls of C. cilidolium and relatives.

Biological notes. — This species is a generalist that occurs on both Eucarya and Apocarya sections and can be found on either leaf surface. Full- grown galls can be found any time from May through October and full-grown larvae anytime after early June, a time range unique for Caryomyia. Development of galls is evidently staggered. In late May through October in central Maryland, galls can be found with first, second, or third instars inside, and second instars can be found in galls into late August. These galls appear to dehisce from the leaves as soon as the third in- stars mature, possibly because of the active larvae inside. Agitation by the full-grown larva in a dehisced gall causes the gall to pop up and down and roll on a level surface. Early dehiscence may be the reason the galls are uncommon on leaves in late season, although occasional galls with live third instars can be found through September and into October, at least in Maryland. In one September trip from Maryland through Arkansas to collect hickory galls, I found not a single example.

Range: AL, CT, FL, GA, KY, LA, MD, MO, OH, TN, VA, DC, WV