AND HABITS OF THE YELLOW DUNG-FLY. 



631 



Adult Feeding. 



Both sexes of the adult fly are predaceoiis on other Diptera. 

 The prey is never caught on the wing, but usually at the moment 

 of settling. The captured fly is grasped firmly by the middle and 

 hind legs, the bristles of the legs helping to make a firmer grip. 

 The prey is caught in such a fashion as to bring both flies in an 

 upright position and the heads one above the other. In this 

 position the wings of the victim are useless, its legs being the 

 only active part. The proboscis is then pressed against the neck 

 and a puncture made through both sides. Attacked flies may all 



Text-figure 1. 



Scatophaga stercoraria, $ , attacking llusca domestica. 



be seen to have the neck stretched and a distinct hole right 

 through it. In this way the nerve-cord is either cut or damnged, 

 causing a partial paral3^sis. The contents of the thorax are then 

 sucked out, at the junction of the neck, as far as the proboscis 

 will reach. A large amount of saliva is secreted during these 

 operations, probably acting as a solvent. The head is then turned 

 round by means of the f I'ont legs, bringing the oral margin upper- 

 most, Another puncture is made inside the oral margin, and the 

 contents of the head, including the eye-pigment, are also' sucked 

 out. Access to the other parts of the thorax is obtained through 



1 



