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 Cecidomyiim; (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 

 Ftg. 521.— Antenna represented by a slight, unbranched fold, 

 male? yP^femaiS 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 



ni*+* 



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 



