462 



DIPTERA 



CHAP. 



that does not agree with the larvae of the allied families having 

 well-marked heads (and therefore called Eucephala), nor with the 

 acephalous maggots of Eumyiidae. 



Fam. 2. Mycetophilidae. These small flies arc much less 

 delicate creatures than the Cecidomyiidae, and have more nervures 

 in the wings ; they possess ocelli, and frequently have the coxae 

 elongated, and in some cases the legs adorned with complex arrange- 

 ments of spines : their antennae have not whorls of hair. Although 

 very much neglected there are probably between 700 and 1000 

 species known ; owing to many of their larvae living in fungoid 

 matter the flies are called Fungus-gnats. We have more than 

 100 species in Britain. Epiclapus is remarkable, inasmuch as 

 the female is entirely destitute of wings and halteres, while 



the male has the halteres 

 developed but the wings of 

 very reduced size. E. scaMei 

 is an excessively minute fly, 

 smaller than a common flea, 

 and its larva is said to be 

 very imjurious to stored 

 potatoes. The larvae of 

 IMycetophilidae are usually 

 very elongate, worm - like 

 maggots, but have a distinct, 



FIG. 221. Mycetobia pallipes. Britain. 



A, Larva; B, pupa; C, imago. (After Dufour.) 



small head ; they are peri- 

 pneustic, having, according to 

 Osten Sacken, nine pairs of spiracles, one pair prothoracic, the others 

 on the first eight abdominal segments. They are usually worm- 

 like, and sometimes seem to consist of twenty segments. Some of 

 them have the faculty of constructing a true cocoon by some sort 

 of spinning process, and a few make earthen cases for the purpose of 

 pupation. The pupae themselves are free, the larval skin having 

 been shed. The Mycetophilidae are by no means completely 

 fungivorous, for many live in decaying vegetable, some even in 

 animal, matter. 



The habits of many of the larvae are very peculiar, owing to 

 their spinning or exuding a mucus, that reminds one of snail- 

 slime ; they are frequently gregarious, and some of them have 

 likewise, as we shall subsequently mention, migratory habits. 

 Perris has described the verv- curious manner in which Scwrjhila 



