TEE SOCIAL WASPS. 343 



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 imme- 

 diately 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 tben 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. 



Polistcs is said also to store honey in the cells from which the per- 

 fect 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 form- 

 ing 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 prot'eid 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 



