92 



BULLETIN 67, UNITED STATES NATIONAL MUSEUM. 



Although many of the brightly colored flies (fig. 156) occur on 

 flowers, more different kinds can be obtained by sweeping herbage. 



In the latter case after one has taken 

 a few strokes the end of the net 

 should be twisted a little, and the tip 

 with its contents placed in a large 

 cyanide jar for fifteen or twenty 

 minutes. On removal the insects 

 will be dead, and one can pick them 

 out leisurely. For flower collecting 

 a small or midget net is very handy. 

 Many species will be found in open 

 groves or the borders of woods, on 

 the trunks of trees, and on the leaves 

 and shrubs. For these a light sweep- 

 ing net is the best, one that can be 

 handled with great rapidity. The 

 gall-making species may be reared 

 from the mature galls, and also those 

 whose larvae occur in fungi and under 

 the bark of trees. 



Diptera suffer more than most 

 insects from shaking about in the 

 bottle or against heavier insects. 

 Therefore it is well to collect them 

 separate from other insects, and to 

 have in the cyanide bottle plenty of 



Fig. 141. — The larva of a mosquito, Culex. 



crumpled strips of blotting or other 

 soft paper. In many cases, espe- 

 cially with the long-legged kinds, 

 they should be pinned in the field 

 soon after capture. Many of the 

 gall-flies (Cecidomyiids) are pre- 

 served mounted in balsam on slides. 

 Doctor Dyar prefers to mount mos- 

 quitoes on points, but they are as 

 well on micro-pins as a double 

 mount. Many bristly Diptera 

 should be pinned a little to the light 

 of the center of the thorax, for a 

 pin through the middle will destroy 

 the bristles in the middle which are 

 of value in classification. In the case of predaceous species the 

 prey when observed should be put on the same pin as its captor. 



Fig. 142. — The screw- worm fly, Compsomyia 

 macellaria. 





