366 ANIMALS OF EGA. Chap. V. 



which have a very long ovipositor, and which belongs 

 to the genus Stylogaster (family Conopsidge). These 

 swarms hover with rapidly-vibrating wings, at a height 

 of a foot or less from the soil over which the Ecitons 

 are moving, and occasionally one of the flies darts with 

 great quickness towards the ground. I found they 

 were not occupied in transfixing ants, although they 

 have a long needle-shaped proboscis, which suggests 

 that conclusion, but most probably in depositing their 

 eggs in the soft bodies of insects, which the ants were 

 driving away from their hiding-places. These eggs 

 would hatch after the ants had placed their booty in 

 their hive as food for their young. If this supposition be 

 correct, the Stylogaster would offer a case of parasitism 

 of quite a novel kind. Flies of the genus Tachinus 

 exhibit a similar instinct, for they lie in wait near the 

 entrances to bees' nests, and slip their eggs into the food 

 which the deluded bees are in the act of conveying for 

 their young. 



