LOCALITY STUDY OF ASTATA BICOLOR[6]
Very often the wind would shake the plant so that the spider or caterpillar would fall to the ground. Under these circumstances the wasp was not at all disconcerted, but, on not finding her prey where she had left it, dropped at once to where it was lying. This is probably only an extension of their ordinary habits. A wasp that takes spiders learns to follow them as they drop from the web on being disturbed. In this they are evidently guided by sight, but perhaps they are also aided by the sense of smell under other conditions,—to the extent, at least, of recognizing the place upon which their prey has lain. With so much to build upon, it is easy to see how natural selection may have perfected the habit. We are delaying a long time over details, but we feel that to invoke an unknown sense is permissible only after a careful study of the daily life of the animals in question has left the problem unsolved.[ill289]
LOCALITY STUDY OF ASTATA UNICOLOR[7]
Among the wasps that first make the nest and then provision the larder, Astata bicolor is one of the most interesting. She makes a permanent abiding-place, and probably uses it until all of her eggs are laid. It is evident that since she comes and goes many times during the several weeks of her occupation, she does not need to make a prolonged study of the environment at every departure. Her first survey, just after the nest is completed, is most thorough; and, as a usual thing, when she first comes out on each succeeding morning, she reviews the situation more or less carefully. Individuals differ in this respect, however, some studying their local habitat much more than others. In this as well as in all other matters our observations are in complete accord with those of Sir John Lubbock, who says: “Indeed, many of my experiences seem to show not only a difference of character in the different species of ants, but that even within the limits of the same species there are individual differences between ants, just as between men.”[8]
This little bug-hunting Astata bicolor made her study in a different way from Sphex ichneumonea. She first flew from the nest to a spot near by and settled there, returning, after a moment, to the nest, or else flying to another resting-place. After pausing in a number of places (in the case of the one followed in the diagram, thirteen), she finished by a rapid zigzag flight. Another wasp of this genus, unicolor, differed from bicolor in not returning to the nest from the different resting-places, and in walking from one to another of them instead of flying, although the last part of the study was made on the wing.
SECOND LOCALITY STUDY OF A. UNICOLOR[9]