The family Mimallonidae contains about 200 species, all Neotropical except for four species which reach into the Nearctic (Lemaire and Minet 1999). The adult moths are heavy-bodied, relatively large, nocturnal, and cryptically colored. The wing margins are often scalloped, and when the moth is at rest, the wings are spread out against the substrate with part of the hindwing showing, features illustrated in these pictures from BugGuide
. A diagnostic feature of the family is that in the adult male antenna, the side branches (rami) become distinctly and abruptly shorter near the tip than on the rest of the antenna, as seen in this BugGuide image
. The proboscis (tongue) is greatly reduced or absent in mimallonid adults, which therefore probably do not feed.