444 



THE STUDY OF INSECTS. 



four to six deep. The larvae crawl over each other so that 

 the column advances about an inch a minute. 



Family CECIDOMYIID^E (Cec-i-do-my-i'i-dae). 

 The Gall-gnats. 



The gall-gnats are minute flies which are extremely 

 delicate in structure. The body and wings are clothed with 

 long hairs, which are easily rubbed off. The 

 antennae are long, sometimes very long, and 

 usually with a whorl of hairs on each seg- 

 ment (Fig. 521); the legs are slender and 

 quite long, but the coxae are not greatly 

 elongate, and the tibiae are without spurs ; 

 the wing-veins (Fig. 522) are greatly reduced 

 in number ; the anal veins being entirely 

 wanting, and vein V wanting or merely 

 FIG. s- Antennae represented by a slight, unbranched fold, 

 male; /. female', To this family belong the smallest of 



enlarged more than 



that of the male. the midge-like flies. On account of their 

 minute size, the adult flies are not apt to attract the at- 

 tention of the young student. But the larvae of many 



vii7 



FIG. 522. Wing of gall-gnat. 



species cause the growth of galls on plants ; some of which 

 are sure to be found by any close observer. Other species 

 arrest the growth of the plants they infest, and thus cause 



