14 AGRICULTURAL EXPERIMENT STATION. 



CHAPTER II. 

 MOSQUITO STRUCTURES AND PECULIARITIES. 



THE ADULT STRUCTURES. 



In order to recognize the difference between mosquitoes so 

 as to determine which species is under examination, it is neces- 

 sary tO' know a httle about the general make-up of the insects. 

 The determination of the particular species that causes the 

 trouble is often a matter of serious importance because, if either 

 of the salt marsh forms prove to be in fault at some point away 

 from the coast, not all the local work, no matter how thorough, 

 can produce a cure. If sylvestris be the offender, some fresh 

 water swamp area falls under suspicion; but if it be pipiens the 

 specimens are home grown and probably from close to the point 

 where they are most troublesome. Anopheles, when found, sug- 

 gests sunken lot areas or pools in low meadows, or a sluggish 

 stream or ditch, and thus the determination of the species at 

 fault should always be the necessary preliminary to the beginning 

 of practical work ; fig-hting in the dark never pays and may result 

 in more harm than good. 



The iig'ure (i) on pag"e 15 should be compared in this 

 connection, and from that it appears that a mosquito body is 

 divided up into three rather well marked parts or sections : the 

 head, the thorax and the abdomen. The head bears the eyes, 

 the feelers and the mouth parts. The thorax bears the wings 

 and legs, or organs of locomotion. The abdomen has no ap- 

 pendages ; but in the male it has a pair of claspers at the tip, and 

 in the female this part is drawn out into a flexible point or tube 

 through which the egg is laid — an ovipositor. 



The most prominent structure of the head is the beak, which 

 is usually less than half and never (in our species) more than 

 two-thirds as long as the entire body. It may be and usually is 

 of the same general color as the body, but in some cases it has 

 a very distinct white band at about its middle and that is one of 

 those readily noticeable features that can be made use of in 

 popular classification. It needs only a magnifying glass enlarg-ing 

 two or three diameters to bring out this and most of the other 

 points here used, very clearly. The character of the biting 

 structures that lie within the beak is elsewhere discussed. Next 

 to the beak, at the base, are the palpi or mouth feelers ; very 



