300 



THE STUDY OF INSECTS 



Family Mycetophilid-iE 



The Fungus-gnats 



These flies are of medium or small size, and more or less mosquito- 

 like in form. They are most easily recognized by the great length of 

 the coxae (Fig. 517), and the fact that all the tibiae are furnished with 



Fig. 517. — A fungus-gnat. (After Johannsen.) 



Fig. 518. — An 

 antenna of a male 

 fungus-gnat. 



spurs. They also differ from the closely-allied families in lacking whorls 

 of hairs on the antennae of the males (Fig. 518), and in possessing ocelli. 



The fungus-gnats are exceedingly numerous both in number of in- 

 dividuals and in number of species. They are often found in great num- 

 bers on fungi and in damp places where there is decaying vegetable 

 matter. They are active and leap as well as fly. 



The larvae of most species live upon and destroy mushrooms, usually 

 I lie wild plants, but sometimes they are pests in mushroom cellars; other 

 species are found in decaying wood. 



The larvae of the fungus-gnats are more or less cylindrical, smooth, 

 soft, whitish in color, and with small strongly chitinized heads which are 

 usually brown or black, and are provided with mandibles and maxillae. 

 There are usually eight pairs of spiracles. 



The pupa is not enclosed in the skin of the larva; but in some genera 

 the transformations are undergone in a delicate cocoon. 



The larvae of some species of the genus Sciara often attract attention 

 on account of a strange habit they have of sticking together in dense 

 patches. Such assemblages of larvae are frequently found under the bark 

 of trees. But what is more remarkable is the fact that when the larvae 

 are about to change to pupae an assemblage of this kind will march over 

 the surface of the ground, presenting the appearance of a serpent-like 

 animal. Such a congregation is commonly spoken of as a Sciara-army- 

 worm. Examples have been described that were four or five inches wide 



