Caryomyia melicrustum Gagne, new species

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

Gall (Figs. 30, 82-83): Common, on Eucarya hickories; on lower leaf surface between veins, usually clustered; 2.0-3.0 mm in height, cylindrical, usually slightly wider than long, conical at base, circular, flat to concave at apex; lateral surface tan to brown, shiny, viscid, the apex orange to brown, crusty, thickly mucillaginous; subtending leaf tissue with conspicuous, extensive, irregular exfoliation surrounding base of gall, corresponding top surface of leaf usu- ally discolored, convex; lateral wall of larval chamber firm, brittle, thin laterally, apical wall usually thicker, larval chamber glabrous, with longitudinal ridges. These galls can sometimes be confused with those of mature, dried C. flaticrustum galls, but galls of the latter lack the conspicuous leaf exfoliation surrounding the base of galls of C. melicrustum.

Affinities. — Galls of this species, short with a conical base set into an encircling leaf socket, are most like those of C. striolacrustum except that they are unlined laterally and sticky to the touch. 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 subtended 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 late May in Central Maryland, one can find young galls not yet completely broken out of the leaf covering and simulating young galls of C. hibicola (Fig. 74) and containing first instars. In mid- to late June, galls are full size but still soft and contain first and second instars. In August one can still see green, softer galls with second instars, but also harder, brown galls with third instars. Pupae emerge from a hole in the thinner walls adjacent to the conical base.

Range: AL, AR, CT, FL, GA, IN, KY, ME, MD, MA, MS, MO, NH, NJ, NY, NC, OH, Ontario, 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/62/mode/1up