The SccttisJi Naturalist. 287 



the house-fly), and they have only a few longitudinal veins (never 

 exceeding five, and seldom more than three, of which the hinder 

 one is the most slender), and one cross-vein near the base of the 

 wings, so that there is no discoidal cell in the wings. The sur- 

 faces of the wings are hairy ; and there is a fringe of hairs along 

 the margins, especially along the hind margin. The antennae are 

 long, and often differ in number of joints in the sexes. The 

 males are smaller than the females, which may be known also by 

 having a slender awl-shaped ovipositor. They shrivel and change 

 colour so much after death that it is often scarcely possible to 

 recognise the species in the dry state ; unless they have been 

 reared so as to afford a clue to their habits and food-plants. 



The number of Cecidomyidae recorded and named is very great ; 

 and it has been found necessary to break up the family into 

 genera, closely allied, yet sufficiently well characterised. Even 

 when this is done, certain of the genera include a very large 

 number of species. The gall-makers fall under the following genera, 

 of which I subjoin only the characters distinctive of each, follow- 

 ing chiefly a useful tabular sketch in Taschenberg's Praktische 

 Znsekten-kunde. 



First and second longitudinal vein (counting \ 



from the costa or front margin) lie so close ( Lasioptera 

 as to be scarcely distinguishable; the second ( Meigen. 

 vein is scarcely half as long as the wing. J 



First and second veins well separated ; second ) 

 vein nearly or quite as long as the wing. j 



Second vein ends a little in front of tip of \ 



wing ; hind or last vein is usually distinctly ( Cecidomyia 

 2. <J forked : Antennae moniiiform, differing in C H. Low. 



the sexes, each joint bears a circle of hairs. / 



Second vein ends at or behind tip of wing. 3. 



Wings usually dull ; thorax humped in front. { Hor ^omyia 

 J r ( H. Low. 



Wings iridescent and shining ; thorax not i 



humped. j ^' 



^Antennae filiform, with hairs of uniform . , , ,. 

 length, alike in the sexes ; species larger I ^spnonclylia 

 than the other Cecidomyidae. ) LlOW ' 



Antennae moniiiform, with a ring of longer 



hairs on each joint, in males 26-jointed, ) jy , 

 in females 13 or 14-jointed ; second vein > P u T 

 arises from first a little way from base of I ' ow * 



1. 



\ 



wing. 



