Caryomyia striolacrustum Gagne, new species

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

Gall (Figs. 31, 84-85): Common, on Eucarya hickories; on lower leaf surface be- tween veins, usually clustered; height 2-3 mm, usually about as wide as long, basal half conical and deeply set into leaf swelling detectable on top surface of leaf as tan to black, conspicuous convexity, apical half of gall short-cylindrical with funnel-like, deep, narrow to wide concavity surrounded by correspondingly narrow to thick walls, center of funnel with short umbo; surface not sticky, yellow to brown, minutely longitudinally striated, the striations partly fibrous on distal half; gall often surrounded and occasionally partially covered by conspicuous, brown, irregularly shaped leaf exfoliation; larval chamber in basal half of gall, wall firm, thin basally, thicker distally than laterally, glabrous, with longitudinal ridges. The shape of the gall most closely resembles that of C. melicrustum but the surface of the latter is mucilaginous and smooth.

Affinities. — Galls of this species, short with a conical base set into an encircling leaf socket, are most like those of C. melicrustum except that they are finely striate and not resinous. 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. — This gall appears to burst out of the leaf after it is mostly formed. In mid- June in central Maryland new galls could be found in various stages of emergence from the leaf epidermis. These contained first instars. By mid-July to mid-August, fully emerged galls contained second instars or third instars.

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/76/mode/1up