DIPTERA. 
55 
genus Sciara, which in North America is said to appear when yellow fever is 
prevalent. But perhaps the most notorious species is the so-called army-worm fly 
(Sciara militaris), which has long attracted attention on account of the peculiar 
habits of the larvse. This fly is completely black, with the exception of its legs, 
which are brownish. The female, which is represented of the natural size at d, in 
the accompanying illustration, and enlarged at c, is larger than the male, and has 
the abdomen terminating in a pointed stylet. In the male, on the contrary, there 
is at the apex of the abdomen a pair of thick two-jointed claspers, and between 
these a couple of small adjacent processes, as shown at e. The extremely small 
eggs are laid by the mother, to the number of about one hundred, upon soil amongst 
fallen leaves on which the larvae feed. On attaining maturity, these larvae measure 
nearly a quarter of an inch long, and have the form represented at a. The 
black head is distinct, and furnished with eyes, and the semi-transparent body 
consists of thirteen segments, some of which are furnished with lateral black 
stigmata. In many countries of Europe where this insect is met with, vast hosts 
of these maggots, forming a compact mass, sometimes several feet long and an inch 
army-worm fly (Sciara militaris). 
a , Larva ; b, Pupa ; c, Female midge ; d, The same (nat. size) ; e, End of abdomen of male ; /, A portion 
of the antenme. (Magnified, except d.) 
or two broad, have been seen at times creeping along at a slow pace through the 
woods like a greyish serpent. The maggots crawl along, not only side by side, 
but also one over the other, all adhering together by their sticky surfaces, and con¬ 
tinually changing their position in the column. At the close of their march, when 
fatigue or want of nourishment causes them to rest for a time, the larvas composing 
a single train collect into a ball, which gradually diminishes in size, and Anally 
disappears by the burrowing into the mould of those that are lowest in the mass. 
For a long while the reason for this peculiar habit remained wrapt in obscurity, 
and perhaps even yet we do not understand its full significance. It has been 
suggested, however, that when the supply of food for the multitude runs short, the 
whole army is moved by a sudden impulse to start in search of fresh supplies. It 
is almost superfluous to add that the peasantry of the countries where this strange 
phenomenon is observable, failing to understand its true significance, have from 
time immemorial regarded it as something supernatural, and as foretelling various 
events in the future, some looking upon it as a sign of the imminence of war, others 
of the destruction of their crops, and so forth. The pupa of the army-worm is 
