102 THE SOLITARY WASPS. 



passed very distinctly. The tiny wasp would pounce upon an 

 aphis, and holding it with the first legs would squeeze its neck 

 gently between the mandibles, rolling it over and over. After 

 a few moments she would pass the aphis back to the second 

 pair of legs and rest for a short time, usually taking this op- 

 portunity to wash her face. She would then bring the aphis 

 forward and squeeze it again. After several repetitions of this 

 process, the apliis would be dropped and another one picked up 

 to be dealt with in the same way, twelve or fifteen being taken 

 in succession before the wasp tired of her objectless industry. 

 In the open, Diodcnitus often alights on one leaf and malaxes 

 her victim and then flies to another and another, repeating the 

 process several times before she finally flies off to her nest. 



We were surprised to find that the wasp never used her sting. 

 Since death is to be the result it would seem that the end could 

 be attained more easily by the injection of a drop of poison than 

 by the careful and laborioLis process which is used. This is 

 not from any rigidity of the abdomen, since while we were 

 handling the wasps they repeatedly tried to sting us, although 

 they are such tiny creatures that they were unable to puncture 

 the skin. It would be of interest to know whether Stigmus, 

 which also captures aphides, and Rhopalum and Crahro, which 

 take gnats, use their stings in killing their prey. We have seen 

 the vigorous Polistes fusca descend upon a caterpillar and 

 reduce it to a pulp by squeezing all the parts with her mandi- 

 bles, not condescending to use her sting at all. It may be 

 that this is the common method of capture in all those cases in 

 which the difference in size and strength between the two 

 actors in the pl^y is such that the wasp need not sting her victim 

 in order to reduce it to helplessness in her hands. This idea 

 suggests that the object of the stinging is primarily to subdue, 

 not to paralyze. 



The next question that confronted us was, where were the 

 nests of Diodwitusl Here we met a difficulty that seemed 

 absurd enough later on but which was very real at the time. 

 We watched the wasps carefully as they prepared for flight, and 



