472 
THE STUDY OF INSECTS. 
Fig. 575.— Microdon , adult and 
larva. 
often mistaken for it. This is the Drone-fly. Eristalis tenax 
(E-ris'ta-lis te'nax). It is common about flowers. The 
larva lives in foul water, where it feeds on decaying vegeta¬ 
ble matter; it is of the form known as “ rat-tailed,” which is 
described below. 
The larvae of the genus Volucella (Vol-u-cel'la) are pre¬ 
daceous, living in the nests of bumblebees and of wasps 
( Vespa ), and feeding upon their larvae. Some of the species 
in the adult state very closely re¬ 
semble bumblebees. 
The larvae of the genus Micro- 
do «(Mic'ro-don) are hemispherical, 
slug-like creatures (Fig. 575 ), 
which resemble mollusks more than ordinary maggots ; they 
are common in ants' nests. 
The larvae of several species that live in water as well as 
some that live in rotten wood are known as rat-tailed mag¬ 
gots on account of a long, tail-like appendage, with which 
the hind end of the body is furnished. This is a tube, like 
that of a diver, which enables the insect to obtain air when 
its body is submerged beneath several inches of water or de- 
caying matter. This tube being telescopic can be lengthened 
or shortened as the insect may need it; and at its tip there 
is a rosette of hairs, which, floating on the surface of the 
water, keeps the tip from being submerged. The larva has 
on the ventral side of its body several pairs of tubercles 
armed with spines, which serve as prolegs. 
Among the more common members of this family are 
the yellow-banded species belonging to the 
genus Syrphus (Syr'phus) (Fig. 576). The larvae 
of these live in colonies of Aphids, and do much 
good by destroying these pests. 
This family is a very large one ; nearly or 
quite two thousand species being known. In 
his monograph of the species of America north of Mexico, 
Fig. 576.- Syr- 
pkus. 
