LASIOPTERA CEREALIS, 195 



Lasioptera, Meigen. 



This genus contains some of the most elegant, but least- 

 known species in the family of Cecidomyiidcs, The}^ are charac- 

 terised by having the two first longitudinal veins of the wings 

 placed near together, and close to the costa, where they are 

 covered with black scale-like hairs ; a white spot is also often 

 placed in the site of the stigma. No vein crosses the middle of 

 the wing, but the posterior or anal vein is present, and forked 

 much in the same manner as in the genera Cecidomyia and 

 Diplosis. Their bodies are very prettily variegated with patches 

 and stripes of white, yellow, or black scales, which are very 

 easily abraded. 



The antennae are peculiar; as in other Cecids they are 

 moniliform, consisting of a number of subglobose joints which 

 are sessile in both sexes ; often somewhat flattened and com- 

 pressed together (especially in the females), and verticillated 

 with short hairs. The particular point about them, however, 

 by which the Lasiopterse differ from almost all the other Cecids 

 is, that they are usually (if not always) shorter, and composed of 

 fewer joints in the male than in the female. This fact seems to 

 have been imperfectly known, and therefore indistinctly described 

 by almost all systematic writers. Meigen, the founder of the 

 genus, says that the antenn£e are many-jointed, and the number 

 of joints varies in different species, but he does not mention the 

 difference between them in the two sexes. Macquart, Zetter- 

 stedt, Walker, Schiner, Van der Wulp, Osten-Sacken, &c., none 

 of them give a distinct account of the difference between the 

 male and female antennae. Winnertz is the only author who has 

 thrown much light upon the subject, and he does not distinctly 

 state that the antennae are shorter in the male than in the female, 

 but says that they are from 12- to S4-jointed, and then refers to 

 the figures in liis 4th plate, in which he gives a very accurate 

 delineation of an antenna of both sexes of L. ruhi, in which he 

 makes that of the male one-third shorter than that of the 

 female, and consisting of seventeen joints, while there are twenty- 

 three joints in that of the female. In his description of the 

 different species he also states that the females have more 

 numerously -jointed antennae than the males in all those of which 

 he knew both sexes, 



S3 



