Natural Enemies. 



121 



middle of the abdomen, most distinct in the male, which 

 also differs from the female in the larger eyes, which meet 

 much more closely on the top of the head than in the 

 female, and in the face being whiter* 



The winter is passed mostly in the pupa state, though 

 doubtless in some cases also in the winged state. 



The flies of this genus are characterized by the shortness 

 of the antennae, and by the attenuated abdomen. The 

 characters given to it are, however, by no means uniform, 

 and as the species generally bear a very close resemblance 

 to each other, and there have been a large number de- 

 scribed in Europe (many of them very inrperfectly), it 

 becomes almost an impossibility to properly determine 

 them. As the sexes often differ materially, it is also, 

 except where they are reared from the larva, difficult to 

 connect them ; and as the colors often become sordid and 

 dull in the cabinet, many of the described species have no 

 real existence. 



The flies frequent flowers, and often congregate and play 

 in swarms in the air. Their eggs are white, smooth, oval, 

 about 0.04 inch long, and are dropped near the food of the 

 larva. In the larva state, these insects mostly feed on 

 leguminous plants, and the carnivorous habit is excep- 

 tional. The species affecting the cabbage, the onion, the 

 radish, etc., have received different names, as brassicce, 

 ceparitm, raphani, etc., but several of them doubtless 

 constitute but one species. A comparison of those reared 

 from the locust eggs with the descriptions of brassicce and 

 ceparum, has not enabled me to discover any constant dif- 

 ferences, and they should perhaps all be referred to radi- 

 cum> Linn. At all events, I feel that it is safest to define 

 the insect under consideration merely as a variety of that 

 species, leaving the proper determination of it to the 

 future monographer of the genus. 



