Caryomyia levicrustum Gagne, new species

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

Gall (Figs. 86-87): Common, on Eucarya hickories; on lower leaf surface between or on veins, usually clustered; height 2.2-3.0 mm, conical at base, cylindrical or flaring beyond, about as wide as long, the apex flat or shallowly to deeply convex, the walls surrounding any apical concavity variously flared outwards, evenly cylindrical, or almost closed to form partial false chamber, the center of apex with short umbo; surface glabrous, not sticky, green to tan; base conical, area of contact with leaf surrounded by thin leaf exfoliation; wall firm, brittle, thin basally, usually slightly thicker apically, larval chamber shiny, smooth, with longitudinal ridges. A variety of gall shapes is included under this heading, but the variation involves only the structure above the larval chamber and the galls are otherwise similar in color and lack of sticky exudate.

Affinities. — Galls of this species appear most like those of C. flaticrustum but instead of being soft and resinous, are hard and glabrous. For further remarks, see under C. flaticrustum. [C flaticrustum: Caryomyia flaticrustum, C. levicrustum, C. melicrustum, and C. striolacrustum are four common, widely distributed species on the Eucarya section with diminutive, more or less discoid galls with conical bases (Figs. 78-87). The main differences among the four species are in the shape and surface texture of the galls. That of C. flaticrustum, has a soft, sticky, concave apex that eventually contracts to form a thick crust. These mature galls simulate somewhat galls of C. melicrustum, except that galls of the latter are sub- tended by a definite exfoliation of the leaf. Larvae of all four species are generally similar with a fairly smooth integument and cruciform spatula. The spatula tooth is barely notched in three species, but acutely pointed in C. levicrustum.]

Biological notes. — In central Maryland galls were noticed as early as mid-June. Galls with second and third instars could be found from then through August. In late March and early April, pupae break out from the side of the galls near the base.

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

- Raymond J. Gagne: (2008) The Gall Midges (Diptera: Cecidomyiidae) of Hickories (Juglandaceae: Carya)^©

Reference: https://www.biodiversitylibrary.org/page/38636615#page/58/mode/1up