etc.; many of these, when they leave their burrows, throw up some sand over the hole so as completely to cover it; how these insects find the spot again after a lengthy chase after spiders or other prey is a marvel; and yet those who have observed carefully say that they come home from long distances with unerring precision. No sense of which we have any knowledge, however accentuated, seems to explain this. To be able to arrive back at a home in an extensive arid sandy plain, where no outward sign indicates its whereabouts, must surely require perception of a different nature from any of those with which we are endowed. Some fossors are subject to the depredations of cuckoos, just as the solitary bees are, but their cuckoos are rarely of aculeate origin. The only ones which I have had any opportunity of studying are the species which nest in bramble stems. The cuckoos which associate with them are some of the smaller jewel flies and Ichneumons: the habits of both these differ from those of the aculeate cuckoos, the jewel flies devouring the larva of the aculeate and the Ichneumon laying its eggs in it. The fossors
THE SOLITARY WASPS
The ordinary wasps are acquaintances of every one, but the solitary or keyhole wasps are not so well known, although they are far from uncommon. They are little narrow black insects striped across the body with yellow, belonging to the genus Odynerus ([pl. A], 9), and might hardly be recognized as belonging to the same family as the true or social wasps. Still they have considerable powers of stinging, and fold their wings lengthwise when at rest like their larger relatives. I dare say some people may have noticed that a wasp's wing sometimes assumes a narrow straight form, quite unlike what it is when expanded. This is due to the wasp being able to fold its wing lengthwise like a fan. The wasp tribe are, so far as I know, the only stinging Hymenoptera which have this power.
