One species, Heliozela aesella (Fig. 1), is common and widespread in Illinois; there is one generation per year. The adult moth is diurnal; it flies near the ground in deciduous forest, on warm days in late April and early May (central Illinois). The combination of size and coloration (bronzy metallic with two white triangles on hind margin of forewing) should render it unmistakably distinguishable from any other microlepidoptera species that occurs in Illinois.
The larva lives inside a distinctive gall-like leaf mine on wild grape, Vitis (Vitaceae), in late May. After it finishes feeding, the larva encloses itself inside a case cut from leaf material (as usual for Heliozelidae), drops to the ground, and remains inside the case as a larva until the following spring when it pupates and emerges. The larva of this species is very unusual among Heliozelidae, in that it retains fully-developed thoracic legs (which are lost in other Heliozelidae, in accordance with their specialization in the leaf-mining mode of life).
Figure 1. Heliozela aesella. Adult, and leaf mines on grape, Vitis (Vitaceae).