94 AN ACCOUNT OF BRITISH FLIES. 



method of leaping, resembling the " hop " of a flea, the hind legs 

 being adapted to this use. When found out of doors, many 

 {MycetopJiila) may be taken in damp ground, and others in plenty 

 near and around fungi, especially when they are somewhat decayed. 

 Many are {Sciophila) short lived ; others {Mycetophila) hibernate,, 

 and appear in the early spring, and according to Heeger, " copulate 

 after a few days, generally in the evening. After six or ten days the 

 female, if the weather is moist and rainy, lays its eggs on the fun.ui 

 growing on old horse-chestnuts, singly, twenty or thirty on the same 

 fungus. The larvK hatch after eight or ten days." 



The " fungus gnats " have not been studied in the same way the 

 Cecids have, and our knowledge of them is not very satisfactory. 

 Recently some good work has been done on the Continent, especially 

 in Russia, by Dziedzicki, whose " Monograph of European Fhronicc"'^ 

 is of great value. The small size and the absence of damage done 

 by the larvae has hindered their study in such detail as has been done 

 in the Cecidomyidae. Some few are certainly injurious, as the 

 species that live upon the " Mushroom," whole frames of this edible 

 fungus being destroyed by these larvae ; but the amount of damage 

 done is small compared to the amount of good which these maggots 

 do in destroying fungi. 



The ? lays her eggs generally on the under surface of the pileus 

 {Mycetophild)^ walking about over the surface first to find a suitable 

 place, then depositing the ova singly. Others {Sciara) lay their eggs 

 in decaying vegetable matter ; they may, as in some of this genus 

 (Sciara) be laid in long strings. The eggs are white and cylindrical, 

 and vary from J to \ of a line in length. 



The larvae hatch after eight or ten days. The account of the 

 larvai is mainly taken from a paper kindly sent me by C. R. Osten. 

 Sacken,t which gives a concise and full description of the structure 

 and habits of Mycetophila larv^. In this paper he gives the follow- 

 ing characters of the larvae : 



" A distinct horny head ; a fleshy labrum, encased in a liorny 

 frame ; horny fiat lamelliform mandibles, indented on the inside ; 

 maxillae with a large coriaceous inner lobe, and a horny outside 

 piece, with a circular excision at the tip ; labrum horny, small and 

 almost rudimentary ; body fleshy, with eight pairs of stigmata." 



The antetmcc are mostly rudimentary {Mycetop/ii/ii. Sa'ara) and 

 spring from a pit on each side of the mouth ; they are often only 

 '' fleshy swellings," but in some {Bolitophila) they are distinctly 



* i[(ir. Ent. Rossland, xxiii. 



f Cliaracters of the larvie of Mvtflophilid.c. 



