MOSQUITOES IN GENERAL 37 



low grass, or other low vegetation, will usually result 

 in the capture of males if there is a breeding place near 

 and it is the proper season. 



Internal Anatomy. - - To be prepared to study techni- 

 cally the relation of mosquitoes to such diseases as 

 malaria and filariasis, the student must be familiar 

 with the internal structure of these insects, which 

 possess specializations of importance. 



The alimentary canal is separable into three regions, 

 the fore, mid, and hind gut, each of which is again sub- 

 divided into distinct parts. Thus the fore-gut con- 

 sists of the sucking tube of the proboscis and the 

 pharynx, including pumping organ and the oesophagus 

 with its diverticular ; the mid-gut consists of a narrower 

 anterior portion (proventriculus) and a wider posterior 

 portion {stomach), the entire structure occupying the 

 thorax and much of the abdomen, being limited by 

 the origin of the five malpighian tubules which indicate 

 the beginning of the intestine or hind-gut ; the hind- 

 gut is bent on itself several times and consists of the 

 ileum, colon, and rectum,' and marked anteriorly by a 

 slight constriction (Fig. 15). 



The salivary system consists of two sets (right and 

 left) of salivary glands, three glands to each set. These 

 organs are situated ventrally in the anterior portion 

 of the thorax. The three central ducts meet to form 

 a single tubule, which again meets the one from the 

 opposite set of glands, uniting to produce the common 

 salivary duct. This common duct empties its contents 



