Caryomyia tuberidolium Gagne, new species

Hosts: Carya glabra, texana, tomentosa, pallida, ovata

Gall (Figs. 46-48): Common, on Eucarya hickories; often in groups, usually on lower, rarely on upper leaf surface, between veins; 3.2-4.0 mm in height, spheroidal, slightly longer than wide, base broadly rounded to truncate in profile, apex with small central nipple surrounded by extensive areola that with pressure easily separates from gall; surface covered with large bumps and resin glands, the sticky exudate in young galls sometimes extruded in hairlike strands, hairless, yellow, tan, or brown, areola paler than surrounding surface; base with wide, deep, circular indentation; wall firm brittle, almost uniformly thin, larval chamber glabrous, with longitudinal ridges. For notes on galls of related species, see under C. cilidolium.

Affinities. — See under C. cilidolium. [C cilidolium: Caryomyia cilidolium, C. hirtidolium, C. tuberidolium, and C. viscidolium form similarly shaped, spheroidal, thin walled galls (Figs. 43-52). At their apex is a large, circular areola surrounding a small central nipple. With a little pressure the circular apex can be broken off as a unit from the rest of the gall and forms the exit from which pupae emerge in spring. Galls of C. cilidolium occur only on bitternut of the Apocarya section of Carya, usually on the lower surface, and are covered with sparse, fine, short hairs. The other three species of this group occur on the Eucarya section. Galls of C. hirtidolium are hairy, much more so than those of C. cilidolium, so that the long hair obscures the gall surface. Galls of C. tuberidolium and C. viscidolium are both sticky, the former very much so and also bumpy and more spherical, the latter merely slightly resinous and smooth. A major difference between these two last species is that C. tuberidolium occurs on the underside of the leaf (except for one example known to me) while C. viscidolium occurs on the upperside. This difference indicates a different egg-laying strategy by the female. The pupal stages are known for all except C. hirtidolium, both sexes for C. cilidolium and C. viscidolium, and the female for C. tuberidolium.]

Biological notes. — In central Maryland, tiny to full-size galls were first noticed on May 24, the galls all with first instars. Second instars were present in some galls by June 25, but most galls still contained first instars through July 8. Third instars began appearing by mid-July and second instars could still be found through Aug. 19. Second and third instars are active when disturbed.

Range: AL, AR, CT, GA, KY, MD, MA, MS, NH, NJ, NY, NC, OK, PA, SC, TN, VA, DC, WV