I have seen this butterfly light on a species of Aphis, Schizoneura tessellata, found on Alnus in crowds on the bark, and from the position of its abdomen it seemed to be going to lay an egg among the plant-lice, but seeing me, she did not. Afterwards I scraped some of these larvæ off a twig of Alder and found a couple of larvæ; I sent them to Mr. W. H. Edwards, and he said that they were F. tatquinius, as I thought. The larvæ were under the bodies of the plant-lice, covered with a thin network of silk to keep the woolly secretion of the Aphides away from them. They were only half grown.