Caryomyia cynipsea (Osten Sacken)

Cecidomyia cynipsea Osten Sacken 1862: 193;
Felt 1918: 47 (Caryomyia);
Gagne 2004: 276, as unplaced sp. of Cecidomyiinae.

Hosts: Carya ovata, tomentosa, glabra

Gall (Figs. 162-164): Rare, on Eucarya hickories; on lower leaf surface, along midrib; 2.6-5.0 mm in height, irregularly spheroid, smooth, hairless, yellow turning brown; base with irregular, shallow, central excavation; woody, polythalamous, with numerous, discrete, irregularly ovoid, smooth walled, larval chambers. This is the only polythalamous gall formed by a Caryomyia. Some other species, e.g., C. aggregata, may appear to be so because their galls will occasionally be found so crowded as to be partially fused, but below each larval chamber will be a basal connection to the leaf. The gall of C. cynipsea has a single connection to the vein.

Affinities. — This species forms the only polythalamous gall in the genus.

Biological notes. — In Spencerville, MD, on July 7, 2004, two separate young galls were found, each containing many first instars in discrete chambers, showing that the gall is truly polythalamous (Fig. 162). Third instars were found in galls from the same site the same year in mid-September. The following spring 3 females were reared, all emerging from separate exit holes from one of the galls.

Range: GA, MD

Caryomyia cynipsea

Carya sp.
Midrib or vein gall
A rounded, irregular, pale yellowish, hard swelling, 12 mm long.

Gall globular, if apex pointed, gall greatly constricted at base, with or without hairs...
Gall smooth...
Gall sessile, irregularly spherical, usually polythalamous...
Caryomyia cynipsea (Osten Sacken)