Caryomyia caryaecola (Osten Sacken)

Cecidomyia caryaecola Osten Sacken 1862: 192;
Felt 1915: 222 (Caryomyia).

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

Gall (Figs. 12-13, 70-71).— Common, on Eucarya hickories; single or in groups, attached to vein on lower leaf surface; 4.8-8.0 mm in height, onion-shaped, upright to leaning, tapered from rounded base to pointed apex; hairless, glabrous, green or yellow, becoming tan to brown; base broadly rounded with large, central conical pedicel in deep, circular indentation; wall hard, of uniform thickness, larval chamber shaped as for gall, glabrous, with longitudinal ridges. This gall vaguely resembles those of C. caryae and C. shmoo in its connection to the leaf and its hard, hairless surface, but it is definitely onion-shaped and, un- like the other two, it is always attached to veins instead of the lamina.

Affinities. — This species may be related to C. caryae (q.v.) and its two close relatives. The gall of the present species shares with the other three a similar recessed, conical base and thin, but hard wall.

Biological notes. — In central Maryland, galls appear by May 23. At first they are light green and soft, but grow very quickly so that by June 9 and until June 15, galls are mostly full-size, green, and brittle, and still contain first instars. By June 17, most galls are hardened and contain second in- stars. Until the second week of August most galls still contain second instars, but an occasional gall contains a third instar. Adults emerge in spring from a subapical hole near the thinnest part of the gall. In Sallisaw, Oklahoma, I saw hundreds of partially developed galls that contained dead, dried first instars. All apparently died of the same cause and gall growth was terminated. Those partially developed galls correspond to the gall drawn in Wells (1916, Fig. 13), a stunted example of the one of the same species he drew in his Fig. 12.

Range: AL, AR, CT, GA, IL, IN, KY, ME, MD, MA, MS, MO, NH, NY, NC, OH, OK, TN, VA, DC, WV

Gall conical, widest at base, tapered to pointed apex, smooth...
Gall smoothly rounded, tapering to pointed apex, light brown...
Caryomyia caryaecola (Osten Sacken)