Gagne Description ²

One of the commonest Caryomyia galls, on Eucarya hickories; usually in clusters, on lower leaf surface between veins; 1.5-2.6 mm in height, depressedspheroidal, often distended to one side, with deep dimple at center top; hair whitish gray, either sparse and not obscuring green to brown shiny surface or dense and obscuring gall surface; base of gall at center with deep, central, circular, shallow depression, the leaf without exfoliation surrounding connection; wall of uniform thickness, firm, woody, the larval chamber invaded from both apex and base by vertical cylindrical intrusions, the apical intrusion bearing crinkly hairs, both intrusions nearly abutting one another at center of larval chamber. Galls of this species vary considerably in hairiness, ranging from sparsely haired (Fig. 113) to so hairy as to obscure the gall surface (Fig. 115). Sparsely and densely haired examples are commonly found intermixed and closely adjacent on a leaf (Fig. 112). The gall is unique for the vertical column through the center of the larval chamber made of the combined apical and basal intrusions of the gall wall. The only other Caryomyia gall with any intrusion is that of C. holotricha, but the intrusion in the latter is only of hair growing inward from the apex of the gall.

Gagne Biology Note ²

In central Maryland, very tiny to full-size galls were found on the same leaflet as early as May 23. Young galls were greenish white turning light yellow with bright white hair. The larvae were all first instars. By June 9, galls appeared full-size and brittle but the larvae were still all first instars. In mid-June through mid-July galls were mostly hard, brittle, and brown to black and contained second instars, but during this time soft galls could still be found with first instars. By the beginning of August galls contained second or third instars and by midAugust more than half the larvae were third instars. Adults emerged in late March and early April from galls collected in New York, New Hampshire, Maryland, and Texas.

Sources and Credits

1. (c) Adam Kranz, all rights reserved, uploaded by Adam Kranz
2. (c) Adam Kranz, some rights reserved (CC BY-SA)

More Info

• iNat taxon page
• Animal Diversity Web
• Biodiversity Heritage Library
• BOLD Systems BIN search
• BugGuide
• CUIC Insect Images
• Field/Photo ID for Flies
• Global Biodiversity Information Facility (GBIF)
• Guide to Hickory Midge Galls
• Guide to Hickory Midge Galls
• Maryland Biodiversity Project
• NatureServe Explorer 2.0
• Systema Dipterorum

iNat Map