DIPTERA. 
101 
larvae of this species, like those of some species of Ceci- 
domyia , is capable of producing creatures like itself. 
The Citlicidce contains the Gnats, or, as they are 
called in some countries, Mosquitoes, i.e ., “ little flies,” 
from muscus , a fly. These insects are plentiful in all coun¬ 
tries, whether arctic or tropical, which abound in wood 
and water. The drawing (Fig. 7) represents the common 
gnat Culex pipiens , the blood-thirsty pest in warm 
summer nights, which disturbs the sleeper. The males, 
which may be distinguished by their pretty hairy an¬ 
tennae, are harmless in this respect; it is the female 
that sucks blood. The eggs are formed in the shape 
of a little raft or boat between the long hind-legs, 
and left to its fate on the water; the larvae must be 
familiar to all who have occasionally looked into the 
rain-tub or stagnant pools of water; they are big-headed 
twisting creatures, that move pretty rapidly in the water 
by jerky motions ; they ascend to the surface of the 
water and expose their tail end (which is provided with 
a long respiratory organ radiated at the tip) to the air, 
with the head downwards ; the pupa, like the larva, is 
active ; it has two ear-like organs on the thorax very 
conspicuous, which are its organs of respiration. These 
gnats sometimes occur in such enormous quantities in 
warm summer evenings as to look exactly like columns 
of smoke, for which, indeed, they have been mistaken. 
Many years ago a dense swarm of gnats was seen issuing 
from the spire of Salisbury Cathedral, which, being 
taken for smoke, gave rise to an alarm of fire. The 
peculiar shrill trumpet-like sound of the female—the 
prelude to an attack on your face or other exposed part of 
the body—is probably produced by the rapid vibrations 
