The mode of carrying their booty is a true instinct. Pompilus takes hold of her spider anywhere, but always drags it over the ground, walking backward; Oxybelus clasps her fly with the hind legs, while Bembex uses the second pair to hold hers tightly against the under side of her thorax. Each works after her own fashion, and in a way that is uniform for each species. The capturing of the victim and caring for it before the hole is made, as in the case of P. quinquenotatus, or the reverse method, pursued by Astata, Ammophila, Bembex, and others, of preparing the nest before the food supply is secured, is certainly instinctive; as is also the way in which some of these wasps act after bringing the prey to the nest. For example, S. ichneumonea places her grasshopper just at the entrance to the excavation, and then enters to see that all is right before dragging it in. Under natural conditions this order is never varied, although the wasp can adapt herself to different circumstances when occasion demands. Again, we see Oxybelus scratching open her nest while on the wing, and entering at once with the fly held tightly in her legs. Each way is characteristic of the species, and would be an important part of any definition of the animal based upon its habits. The general style of the nest depends upon instinct. Trypoxylon uses hollow passages in trees, posts, straws, or brick walls; Diodontus americanus, a member of the same family, always burrows in the ground, as do Bembex, Ammophila, and Sphex. In the case of Trypoxylon the passage may be ready for use or may require more or less preparation; the instinctive part is the impulse that requires the insect to use a certain kind of habitation. Any one familiar with T. rubrocinctum would never look for her nest in standing stems or under stones; to use Mr. Morgan’s test, he would be willing to bet on the general style of the dwelling–place. All of these acts are similarly performed by individuals of the same sex and race, not in circumstantial detail but quite in the same way in a broad sense. Variation is always present, but the tendency to depart from a certain type is not excessive. In Cerceris the burrow is tortuous, this style of work being common to many species in the genus, and very characteristic. No Sphex nor Ammophila constructs any such tunnel. The adherence of all the members of a species to a certain style of architecture is, then, due to instinct.