[Illustration: FIG. 12.--Solitary Wasp dragging a Caterpillar to its Nest (after Peckham).] The mode of carrying their booty is in these wasps instinctive, and relatively uniform. _Ammophila urnaria_ grasps the caterpillar, near the anterior end, in her mandibles, and carries or drags it beneath her legs, walking forwards. It is generally but not always with the ventral surface uppermost. _Pompilus_ takes hold of her spider anywhere, but always drags it over the ground, walking backwards. _Oxybelus_ clasps her fly with her hind legs; _Bembex_ with the second pair. Each works after her own fashion in a way that is relatively uniform for each species. The general style of the nest, its mode of construction, and its method of closure, are always performed, says Dr. Peckham, by each species in a similar manner, not indeed in circumstantial detail, but quite in the same way in a broad sense. Variation or modification is always present, but the tendency to depart from a nest of a given type is not excessive. Some dig in the ground curved tunnels, with or without one or more chambers. Others bore into decaying wood; others use straws, or make tunnels in bramble stems; while the mud-daubers build cells in which to store the food and lay the egg. This is sometimes deposited on the first, sometimes on the last, sometimes on some intermediate victim, but generally in much the same place and position. _Ammophila_, for instance, lays it on the side of the sixth or seventh segment--that is to say, in about the mid position. Some species first capture their prey, and then make the nest in which it is to be entombed. Others first prepare the nest, and then carry or drag their prey to it--often from considerable distances--quite irrespective of what seems to us the more appropriate method of the two under the particular circumstances of the case. And the way in which the victim is dragged into the nest is similarly a matter of inheritance. Each way is characteristic of the species concerned, and would be an important part of any definition of the animal based upon its modes of behaviour. For example, a _Sphex_ places her grasshopper just at the entrance of the nest, which she then enters herself before dragging in her prey by the antennæ. When the wasp was in the hole, Fabre moved the victim a little way off; the wasp came out, brought the grasshopper to the entrance as before, and went in a second time. This was repeated about forty times, each time with the same result, until the patience of the naturalist was exhausted, and the persistent wasp took her booty in after her appropriate fashion. She must place the grasshopper close to the opening; she must then descend and examine the nest, and, after that, must drag it down. Nothing less than the performance of these acts in a certain order satisfies her instinctive impulse.