In this species the male does not always come out of the nest when the female brings a spider, the nest being enough larger than in rubrocinctum to accommodate them both comfortably. As a usual thing, however, he enters on the back of the female. The spiders brought by albopilosum are larger than those used by rubrocinctum. They sometimes bring such heavy specimens of Epeira insularis that they are carried with difficulty, the wasp alighting and dragging the spider into the hole instead of flying directly in as usual. We watched a number of albopilosum nests during the second summer, finding them in several instances through the loud humming of the female while she was pushing the spiders into her hole. From our not very extensive study of the spiders taken by this species we are of the opinion that some are killed at the moment of capture, while others that are only paralyzed die in the nest from day to day. Mr. W. H. Ashmead has noted that albopilosum stores its nest with aphides, but in the cases that we observed they used only spiders. There can be no mistake on this point, as we more than once took the spider from the wasp as she was entering the nest. In a recent letter Mr. Ashmead says that his notes were made in the field, and that he probably mistook some closely allied species for this one. We are not as familiar with the habits of T. bidentatum as with those of the other two, but we have a few notes relating to the female. This little worker is the smallest of the three, and like her sisters is a confirmed spider–hunter. Once, when out among the raspberry bushes, we had the good fortune to witness a capture. The wasp seized the spider, as it rested on a leaf, by the top of the cephalothorax, and, holding it firmly, curved her abdomen under and stabbed the ventral face of the cephalothorax. All her motions were deliberate, and after the operation she delayed a moment before picking it up by a leg and flying off. We often found raspberry stems which had been filled with spiders by this wasp, but we do not know the length of time required for the development of the egg, nor how long the larva eats before pupation. The cocoon is very different in appearance from those of rubrocinctum and albopilosum, being exceedingly long, slender, and almost white, instead of short, wide, and brown. The perfect insects come out in September, and the last cocoon formed is the first one to hatch. This was also true of the cocoons of rubrocinctum formed in straws.