274 WASPS 



are those of the Eumenidce or solitary wasps and of the 

 Fossores or digger wasps. The grubs of all three groups 

 are mainly carnivorous ; those of the solitary and digger 

 species appear to be exclusively so, and the mothers are 

 skilled housewives. Some make cells of porcelain formed 

 of clay moistened with saliva ; others dig out burrows in 

 the soil to serve as nurseries; a third kind tunnel into 

 timber ; while a fourth family make shift as burglars and 

 parasites on bees and other insects. Each is true to the 

 traditional craft of its species ; but how is that tradition 

 transmitted through the generations ? The life-span is 

 bounded by a single season, during which the creature 

 passes through a series of strange metamorphoses. 

 Scarcely ever can an individual of one generation witness 

 the earliest stage in active life of the next, and, except in 

 the brief intercourse of the sexes, these solitary workers 

 hold no communion with each other. Provision for off- 

 spring which they shall never see is the one purpose for 

 which digger wasps labour with unceasing industry and 

 unerring skill. At least the females do; for the males, 

 submitted to a human standard of ethics, are worthless 

 fellows, never doing a single turn of work, and apparently 

 unaware that there is any work to do. 



The number of digger wasps is so vast (upwards of a 

 thousand distinct species of Mutilla alone have been 

 classified) that it would require several volumes to describe 

 the infinite variety and complexity of their domestic 

 economy. The feature distinguishing the whole group of 

 diggers is artistic discrimination in the use of stings. 

 Some prey on caterpillars ; others on the grubs of bees 

 or beetles; while the Pompilidce, the most numerous 

 family in the group, make spiders their special game, and 



