Q. Can you help me identify the very large moth that appears just for a day or two on the side of my house at this time of year? And is it harmful?

A. It is probably a Cecropia moth seeking a mate. These moths are a quite distinctive dark reddish-brown, with silver lines and crescent shapes on their 5- to 6-inch wings. After mating and laying eggs, the females deposit eggs on future food sources (apple, white oak, black cherry or birch trees) for the developing caterpillars. The large caterpillars take all summer to achieve full size, then form cocoons on low shrubs and pupate over the winter, emerging as large moths in early summer. Although caterpillars in general are voracious eaters, the Cecropia larvae are rarely found in large enough numbers on the same tree to warrant any controls.