Rubrocinctum was more conveniently studied, and through July and August we watched the comings and goings of these little wasps. They were very good–tempered, never resenting our close proximity nor our interference with their housekeeping. By working hard they could prepare a nest, store it with spiders, and seal it up all in the same day. This we have seen them do in several instances. In other cases the same operation takes three or four days. In the second summer that we worked with them we found one very energetic mother that stored four nests in one day. It had rained hard on the twenty–sixth of July, and no wasp works in such weather. On the afternoon of the twenty–seventh we took a straw just as the little mother was bringing in a spider. We opened it and found that the innermost cell contained eight Epeirids, with an egg on the abdomen of the last one taken in; the second cell was provisioned with ten spiders, with the egg on the seventh, so that three had been brought in after it was laid; the third cell had the egg on the last spider, as did also the fourth. All of these eggs hatched on the twenty–ninth,—the two outer ones, that were laid last, between eight and nine o’clock in the morning, and the two that were laid earlier between two and three in the afternoon. This was the biggest day’s hunting that we have ever recorded for any of our wasps. With both species (T. rubrocinctum and T. albopilosum), when the preliminary work of clearing the nest and erecting the inner partition has been performed by the female, the male takes up his station inside the cell, facing outward, his little head just filling the opening. Here he stands on guard for the greater part of the time until the nest is provisioned and sealed up, occasionally varying the monotony of his task by a short flight. As a usual thing all the work is performed by the female, who applies herself to her duties with greater or with less industry according to her individual character; but the male doubtless discharges an important office in protecting the nest from parasites. We have frequently seen him drive away the brilliant green Chrysis fly, which is always waiting about for a chance to enter an unguarded nest. On these occasions the defense is carried on with great vigor, the fly being pursued for some distance into the air. There are usually two or three unmated males flying about in the neighborhood of the nests, poking their heads into unused holes, and occasionally trying to enter one that is occupied, but never, so far as we have seen, with any success, the male in charge being always quite ready and able to take care of his rights. The males, however, made no objection when strange females entered the nest, as they sometimes did by mistake, nor did the females object to the entrance of a strange male when the one belonging to the nest happened to be away; but in such cases the rightful owner, on his return, quickly ejected the intruder.