DIPTERA. 101 



larvae of this species, like those of some species of Ceci- 

 domyia, is capable of producing creatures like itself. 



The Gulicidce contains the Gnats, or, as they are 

 called in some countries, Mosquitoes, i.e.y " 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 plpiens, 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 ia 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 vv^ith 

 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 



