BEHAVIOUR 105 



some six inches away. The Osmia failing to find the shell 

 where she had left it, proceeded to hunt about until she 

 recovered it, and then for several subsequent journeys made 

 her flight to its new station by way of its two former resting- 

 places. Afterwards, however, she was seen to go directly 

 to the new station : " Little by little the images of the former 

 places of her nest are effaced in the memory of the insect." 

 E. L. Bouvier (1920) remarks on these observations that such 

 insects " know how to manage things and to meet the most 

 unexpected situations. They do not act as automata ; the 

 memory that guides them in these circumstances seems 

 indeed from its essential characteristics to belong to the 

 same degree of psychism as the human memory." It may 

 be doubted, however, whether such behaviour, remarkable 

 and instructive though it is, can be regarded as of '' the 

 same degree " as the memor}^ of man. 



Of all the unusual modes of behaviour by insects of 

 which we have reliable record few have appealed more 

 strongly to the imagination of naturalists than the work of 

 the North American digging-wasp Ammophila urnaria, that 

 captures, stings, and buries caterpillars as a food supply 

 for her grubs. Most of the species of Ammophila dig their 

 nests in the soil before hunting for prey to deposit in them, 

 and a completed nest may harbour four or five paralysed 

 caterpillars with as many Ammophila eggs. One of these 

 females covers the mouth of her burrow with pellets of earth, 

 but normally never fails to find the nest on her successive 

 returns from the hunting. When the nest is fully stored 

 and the eggs are all laid, the wasp finally closes up the 

 mouth. The Peckhams (1898, pp. 6-32), who paid especial 

 attention to the habits of these wasps, comment on the 

 difference in behaviour shown by individual females in the 

 work of nest-closing, some being much more careful in 

 performing their task than others. " Of two wasps that 

 we saw close their nests on the same day, one wedged two 

 or three pellets into the top of the hole, kicked in a little 

 dust, and then smoothed the surface over, finishing it all 

 within five minutes. . . . The other worked . . . for an hour. 



