Heliozela aesella

Heliozela aesella Chambers.

The larvae produce flattened galls on leaves of grape. The gall consists of an irregularly shaped thickening of the leaf, situated on a vein and extending to either side of it, the area involved rarely being more than one centimeter in diameter, with a thickness perhaps three or four times that of the leaf itself. The galls are paler in color than the rest of the leaf and about equally distinct on the upper and lower surface. The larva consumes most of the leaf substance in the gall, especially in a large oval area, where only the epidermis is left. At maturity it cuts from this area, an oval case, in outline similar to that of Antispila. This case, however, does not remain flat, but is rolled up into a spindle, which falls to the ground. The spindle is flattened at each end, where a semi-circular fissure is left, guarded by the closely appressed, flattened, projecting ends. The spindle is then covered with fine panicles of earth, and lined throughout with close whitish silk. Within this cocoon an inner pupal chamber is partitioned off; this tapers to a point at the posterior end, but at the anterior end is closed by a flat transverse sheet of papery silk. In emergence, the pupa pushes up this sheet of silk and protrudes from the cocoon to the side of the median line between the flat projecting ends.

The moths appear in the latter part of April and in early May; the galls develop on the expanding leaves and are fully formed by the beginning of June. The larvae reach maiurity about the middle of June. There is but one generation a year. 

In the vicinity of Cincinnati I have found the galls only on Vitis cordifolia [vulpina]. In other localities it occurs on other species of grape; specimens of the work on a cultivated variety from Boston were submitted to me for identification some years ago by Mr. J. L. King, at that time on the staff of the Ohio Agri- cultural Experiment Station. In a letter accompanying the specimens he wrote that it has also been observed in the grape belt in northern Ohio. 

Notes on microlepidoptera with descriptions of new species