222 SOCIAL LIFE IN THE INSECT WORLD 



From truffles dug up in a spoiled condition, peopled 

 with vermin, and placed in that condition, with a bed 

 of fresh sand, in a glass jar, I have in the past obtained 

 a small red beetle, known as the truffle-beetle (Aniso- 

 toma cinnamomeuy Panz.), and various Diptera, among 

 which is a Sapromyzon which, by its sluggish flight 

 and its fragile form, recalls the Scatophaga scybalaria, 

 the yellow velvety fly which is found in human excre- 

 ment in the autumn. The latter finds its refuge on the 

 surface of the soil, at the foot of a wall or hedge or 

 under a bush ; but how does the former know just 

 where the truffle lies under the soil, or at what depth ? 

 To penetrate to that depth, or to seek in the subsoil, 

 is impossible. Its fragile limbs, barely able to move a 

 grain of sand, its extended wings, which would bar 

 all progress in a narrow passage, and its costume of 

 bristling silken pile, which would prevent it from 

 slipping through crevices, all make such a task impos- 

 sible. The Sapromyzon is forced to lay its eggs on 

 the surface of the soil, but it does so on the precise 

 spot which overlies the truffle, for the grubs would 

 perish if they had to wander at random in search of 

 their provender, the truffle being always thinly sown. 



The truffle fly is informed by the sense of smell 

 of the points favourable to its maternal plans ; it has 

 the talents of the truffle-dog, and doubtless in a higher 

 degree, for it knows naturally, without having been 

 taught, what its rival only acquires through an 

 artificial education. 



It would be not uninteresting to follow the Sapro- 

 myzon in its search in the open woods. Such a feat 

 did not strike me as particularly possible : the insect 



