We had watched a wasp for some time as she carried her spider from place to place, and finally saw her take it into a crevice among some rough lumps of earth which she had previously examined. We expected one of the long spells of eventless waiting to which she had accustomed us, but on lying down and peering into the hole we found that there was an opening on the further side, for a ray of light feebly penetrated the interior. Moving about in this dim illumination was our wasp, and after a little, we could see, quite distinctly, that she was digging a hole. This then is her method—to find some sheltered hiding–place where she may secretly make her nest, that no creature may know where her treasure is hidden. We have twice seen a marginatus pick up her spider and fly with it backward for a long distance—as much as four or five feet. This recalls the wasp which is said to fly backward before a moving horse and catch the flies that are hovering over it. P. marginatus is not troubled by any notion as to the family connections of the spider that she takes. Anything will do provided she is strong enough to overcome it and carry it to her nest. The effect of her sting is quite variable, since in some cases the victim was killed at once, while in others it was but little affected in the beginning and lived for eighteen or twenty days. At eleven o’clock on the morning of a warm day in mid–August we saw the steel–blue Pompilus scelestus dragging a big Lycosid across a field. The spider was sixteen millimeters long and wide in proportion, while the wasp was but thirteen millimeters long and very slender, so that the weight of the spider was at least three times that of its captor. The necessity for going backward was evident in this case, but the wasp moved rapidly considering the load that she was dragging. As she worked her way along she made frequent pauses, stopping for two or three minutes at a time in some little hollow, or under leaves or weeds. She spent a good deal of time, during these pauses, in cleaning herself, and a good deal of time also in doing something to the spider which we could not understand. She seemed to be biting the legs, near the body, beginning with an anterior leg on one side and working backward, and then repeating the operation on the other side. She went through this squeezing process again and again, and to us it looked as though she might be trying to force back the juices from the legs into the body preparatory to cutting them off; but after a time she would seize her prey and start on again. She had made her way along in this fashion for some ten feet, when a second wasp appeared and alighted on a weed near by. This interloper was a trifle smaller than the other, and from her actions was evidently greatly interested in the paralyzed spider. When the Pompilus stopped for a moment the other moved from stem to stem in a stealthy manner just as a cat stalks a bird. The rightful