SOCIAL WASPS 275 



enlarged to allow it to pass in, the construction of mud 

 cells by some, of earthy hollows by others, are fixed 

 habits of the several kinds of wasps. 



Nevertheless, a certain improvement in their 

 habits, due to experience, is undoubtedly exhibited 

 by many. The adoption of chimneys or eaves of 

 buildings is an improvement on the older method of 

 using hollow trees or shelving rocks. Again, the 

 spider-hunter has found that to hang up its prey 

 in a fork while finishing the burrow, instead of leaving 

 it on the ground, is a safeguard against ants. She 

 has also found that by cutting off the spider's legs 

 more booty may be stored in a given space, and 

 though exceedingly conservative in going through the 

 operation by putting it down at the burrow's edge, 

 investigating the nest and then pulling the spicier down 

 into it, yet she is not such a slave of custom as to be 

 unable to adapt her action to changed circumstances, 

 and if the spider is repeatedly removed while the 

 wasp is in her burrow she will ultimately abandon the 

 preliminary survey and drag her prey straight down, 

 going backwards. 



Social Wasps. — The chief advance made by these 

 more familiar wasps over the solitary species lies 

 in the evolution of the worker. The care of the young 

 in the solitary wasps is entirely the work of the mother, 

 who is both queen and worker. For the first few weeks 

 of spring the same is true of colonial species, but, later 

 on, the construction, protection, and provisioning of the 

 nest is taken over by the workers, whilst the queen, 



