SOCIAL INSECTS 127 



In concluding this chapter it may be noted that the larvae of 

 many insects are found feeding together in "companies", which 

 have hatched out from batches of eggs laid at the same time 

 and place. Probably the most remarkable case of associated 

 larvae is afforded by the maggots of certain of the little two- 

 winged flies known as Fungus Gnats (MycetophilicUz). One of 

 these is familiar as the " Army Worm " (Sciara militaris) of 

 Europe, and allied forms are native to the United States. The 

 maggots live among rotting leaves, and are sometimes found 

 moving from place to place, united together by sticky threads, 

 and writhing along like a snake. The largest armies of this 

 sort may include millions of individuals, and are stated to reach 

 an extreme length of 100 feet, with a breadth of 6 inches, and 

 a depth of i inch. The migrations are probably dependent on 

 the question of food-supply. 



