54 Psyche [April 



without biting the skin of its prey and its feeding is indicated 

 only by the rhythmic movement of its body, but as it increases 

 in size it may be seen to bite rather ferociously at its caterpillar, 

 sinking its mandibles and even its entire head into the now 

 lacerated bod3^ Growth is rapid and usually the food is con- 

 sumed to the last bit, even the heads being eaten by some of the 

 more voracious individuals. When all the food is gone the larva 

 may be observed moving about its cell, its mandibles constantly 

 working along the walls. Whether it is searching for more food 

 or attempting to begin its cocoon is not entirely evident. At 

 any rate, the result of this activity seems to be that all the de- 

 tritus in the cell, including the excrement of the caterpillars and 

 whatever of the food supply may occasionally remain uneaten, 

 becomes gathered at one end or along the lower wall of the cell, 

 so that it does not interfere with the spinning of the cocoon. 

 Before actually spinning the cocoon the Ancistrocerus larva 

 makes a rather coarse-meshed network closely applied to the 

 walls of the cell, entirely lining it and excluding all debris. The 

 cocoon is variable in shape, irregularly cylindric-elliptical with 

 one of its ends and its lower surface touching the walls of the 

 cell, usually at the inner and lower end. It is tough, closely 

 woven, translucent and semi-transparent, usually of a pale 

 brownish tint with a slight silky lustre. Figure 2, though per- 

 haps of a different species, illustrates the position of these 

 cocoons in situ. Pupation does not take place immediately, the 

 larva remaining quiescent in the cell for from five to seven days. 



As in most nidificating Hymenoptera which construct 

 similar nests, the outermost occupant of the nest is the first to 

 emerge, though it is necessarily the product of the most recent 

 egg laid by the builder. All the males reach the adult stage at 

 about the same time, byt until the one nearest the entrance 

 makes its escape, there appears to be no attempt on the part of 

 the others to break out, though they often may have already 

 broken from their cocoons and are free to emerge as soon as the 

 way is clear. Once the first male has made its escape the others 

 follow in rapid succession, the females only remaining after the 

 males have been gone for some little time. 



