the path by which she had left it. Experiments were also made by moving the nest as soon as the locality-study had been made, and seeing whether the wasp returned to the place where the nest had been. Invariably the wasp did return to the exact former site of the nest, but considerable variation was shown in the ability to find the nest in its new location. One wasp had no difficulty, when the nest had been moved a distance of eighteen inches; others were unable to do so if moved more than eight inches. In one instance, the site of the nest was changed while the wasp was sipping honey from a dish about fourteen inches away. Returning, and not finding its nest in the usual place, the wasp, in circling, reached the honey dish once more, and again started for the nest along essentially the same path. This was repeated eight times before the wasp in its explorations finally reached its nest and rested there. The whole performance looked as though the wasp were consciously using the honey dish as a landmark. It started out from this point each time, the same way as a person might, when he became aware that he was making some mistake in finding his way to a desired destination.
It would be interesting to speculate on the meaning of the various actions described above. What sense best serves Polistes in finding its way about? Does it actually see and make a mental note of the various factors of its environment? Or does a mere blind following in response to other sense impressions, namely, the olfactory, serve its purpose? Theory is fascinating, but with the slight data at command, it is hardly profitable. Observation shows that the wasp instinctively flies toward the light; its course is also materially affected by currents of air, such as draughts in a room where it is held captive. Mechanical response to these two influences will, in this case, usually serve to liberate it without the use of any other sense or faculty. Again, the antennae seem to play an important rôle in orienting the insect. Accidental loss of one antenna in one case retarded the finding of the nest. Further, the flight in circles, when leaving or approaching the nest, might be interpreted as due to the difference in stimulation of the antennae of the two sides—the side toward, and the side away, from the nest; and the flight straight to the nest, when the wasp has poised for a moment with both antennæ directed toward the nest, seems to add evidence in favor of this view. However, further experimentation is necessary before it is possible to attempt a satisfactory explanation.
During the cold days of autumn, when there are no more larvae to rear, about the only activity observed on the nest is that occasioned by the home-coming of a member of the wasp family. This one is tumultuously set upon by the half dozen wasps nearest him, each of which is favored with an embrace which is amusingly like the affectionate demonstrations shown on the return of a human being to his family
