98 DIPTERA. 



few species, all of which are parasitic on mammalia and 

 birds, feeding on the substance at the roots of the hairs 

 and feathers. 



The first section is divided into two large sub-sections, 

 to which, from the characters of the antennae, the names of 

 Nemocera and Brachycera have been given. In the first 

 the antennse are long and thread-like, with a great number 

 of joints, such as those of the Gnats, Daddy long-legs, 

 etc. In the second sub-section the antennae are short 

 and often consist of only three joints of an equal size, 

 the last being often furnished with a long bristle. Be- 

 sides the Nemocera and Brachycera there is a third sub- 

 section, which contains a very few species, the Hypocera, 

 in which the antennae are situated not between the eyes, 

 but low down near the mouth. The Brachycera sec- 

 tion is by far the largest. The Nemocera has been 

 divided into two families by Mr. Francis Walker ; space 

 of necessity compels me to confine my remarks to a few 

 only. 



The Mycetophilidce are chiefly fungus-eating flies, 

 eaters of decayed vegetable matter, in their larval con- 

 dition ; they inhabit woods, are small, and have legs 

 formed for leaping. The larvae are common in the 

 growing stems of hollow-stalked agarics. As consumers 

 of decayed vegetable matter they are serviceable. 



The Cecidomyzidoe or gall-gnats are, to use Mr. F. 

 Walker's words, " the most elegant and delicate little 

 creatures in tiie whole of the Dipteral The wings 

 are often beautifully iridescent ; the antennae long and 

 graceful. The larvae, fleshy oval grubs, feed on varices 

 living plants, and are thus more or less injurious to 

 vegetation ; some form galls, others feed on decayed 



