542 Introduction to the Study of Science 



gutters, rain and drain pipes, clogged-up eaves or exposed tanks 

 in attic or basement, cesspools, imperfectly covered wells, and 

 in short any vessel containing a supply of dirty water in which 

 a mosquito may deposit her eggs. 



The Culex differs in habits from the forest or marsh mosquito, 

 the Anopheles, which lays her eggs in pools of water, shallow 

 ponds, marshes, stagnant or sluggish streams. Small lakes 

 in public parks of large towns or cities, irrigation ditches in 

 which water may stand for a considerable period or flow very 

 slowly, may account for the occasional presence of the forest 

 mosquito with the common variety. The two varieties are 

 easily distinguished by the fact that both tend to remain near 

 their breeding places. For this reason the common Culex will 

 always outnumber the marsh or forest kind in or near any com- 

 munity. The converse is true in the vicinity of woods or marshes. 



The color and markings of the Culex are plain and un- 

 obtrusive. It is usually gray with a tendency toward brown, 

 but sometimes black. When it rests on a wall or ceiling, its 

 position is characteristic (Fig. 161). It stands with its body 

 nearly parallel to the surface and is apparently " humpbacked." 

 The palpi are quite short in comparison with the proboscis. 



The Anopheles is generally easily recognized. Its spotted 

 wings are often taken as its chief characteristic and from this 

 it has the name Anopheles maculipennis (spotted wing). But 

 this feature varies among the several varieties. There are 

 also groups of other species that have spotted wings. This 

 feature, if taken alone, is therefore unreliable in identifying the 

 insect. The plainest and most certain features are the feathery 

 palpi of the mouth, which are quite as long as the proboscis. 

 A characteristic of the Anopheles which cannot be mistaken is 

 its standing or resting position. It always holds its body in a 

 straight line and at a wide angle or nearly perpendicular to the 

 surface upon which it is standing (Fig. 162). 



Stegomyia. Another species of the order to which the Culex 

 and Anopheles belong, is the Stegomyia calopus, sometimes called 



