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Page:Popular Science Monthly Volume 61.djvu/349

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343
THE SOCIAL WASPS.

omitted, although the movements of the anterior usually precede those of the posterior appendages.

Then the wasp makes frequent careful inspection of the cells of her nest. She may return every few minutes in the interval of her other activities apparently for the sole purpose of satisfying herself that all is well. To test the wasp's power of observation I have several times cut away a bit of the cell wall. In one case, the mutilation was immediately detected and an attempt made to repair the breach. Once, one of the eggs was replaced by one from another nest. When, in the course of the customary examination, this cell was reached, the wasp paused, gazed long and fixedly, as if unable to believe the evidence of her senses, and then with signs of great agitation, cleaned the cell out and deposited a new egg of her own. To ascertain whether the mucilage by which the egg was attached was the exciting cause, several eggs were smeared with it and left in their original positions. In this case the mucilage was carefully removed, but the eggs were left untouched.

Polistes is said also to store honey in the cells from which the perfect imagines have emerged. In the height of the season these cells are used a second time for the development of the young. They are then carefully renovated before the egg is deposited. I have never yet found honey stored in the nests taken, but in two nests which were kept indoors for the purpose of experimentation, many of the cells were found to contain a few grains of perfectly transparent sweetish substance which undoubtedly had been elaborated from the sugar solution forming the food store of the little colony.

 

The Larval and Pupal Periods.

The sole activity of the young during the three weeks' larval period appears to be the feeding on the elaborated nectar and proteid matter furnished by the mothers or the workers. At the end of this time the larva spins a silken lining and a covering for its cell. This is done by passing the head from point to point of the cell wall while a glairy fluid issues from its mouth and hardens into a delicate silken thread. I have noticed a considerable difference in the form of the cell covering. Under normal conditions, the cell is lengthened by the workers or queen to suit the increasing size of the larva, but in captivity the wasps cease the work of construction though they may still continue to feed the larva?. The cell is therefore too short for the full-grown larva. In such cases it not only lines the cell but extends the wall with the same silken substance, finally capping it with a dome-shaped cover. This apparent forethought on the part of the larva is entirely accounted for, when we see that in spinning its cocoon the larva begins near the bottom of the cell, gradually approaches its mouth and finally stretches as far as possible beyond it. If the cell wall is already sufficiently