Grape Leaf Folder Moth – Desmia maculalis
Family Crambidae – Crambid Snout Moths
Live adult moths photographed at Saint Louis, Missouri. Wingspan = 15 mm | Hodges #5160
The grape leaf folder is a common and widely distributed species that is a minor pest of grapes in the United States. In California severe outbreaks have occurred in restricted areas during some years. These outbreaks have been associated with failures of parasites to attain their normal levels. In Florida, the grape leaffolder has done substantial damage to grape leaves in September and October when growers have discontinued their spray programs after harvest. Excessive defoliation may deplete the food reserves in the vine sufficiently to reduce the size of the next crop.
This moth was hiding underneath the leaves in the underbrush – there was no way to photograph it except lie down on the ground and take pictures upside down. Yikes. I wish I could have gotten a full-on shot, but this moth was not cooperating. A very strikingly colored moth for one so secretive. I suppose that’s why it must hide all the time – it has no camouflage, at least in the setting I saw it.
Adults have a wingspan of 15 to 25 mm (1 inch or so). The wings are dark brown, almost black, with a silvery or bluish iridescence. The forewings in both sexes have two nearly oval white spots. The hind wings of the male have one white bar which in the female is partly or completely divided into two spots. Both sexes have various amounts of white on the fringes of the wings and parts of the head, body, and legs.
The antennae in the male appear thickened and notched near the middle, while in the female they are uniform and threadlike. Adults of other species of Desmia and certain other similar species in Florida have the white spots of the wings much more linear or are obviously different in number of spots or some other characteristic.