37 



The mosquito commences its operation of stinging by tentatively 

 exploring the skin with the point of its proboscis until it finds a suitable 

 spot. It them takes a firm position upon its six 

 feet (sometimes the two hing legs are raised 

 above its back), the thorax is strongly bent down 

 while the head and the proboscis assume a ver- 

 tical position. Next, with the naked eye or, bet- 

 ter, with the assistance of a magnifiying glass, 

 the sheath is seen to bend backwards, at its up- 

 per part, gradually assuming the shape of an 

 horizontal < the two branches of which gra- 

 dually come closer together as the sting pene- 

 trates deeper into the skin. The sting is then 

 seen as a very slender wire stretching between 

 the extremities of the hori- 

 zontal <^ figured by the 

 sheath, and moving up and 

 down in unison with the 

 maxillary palps, until a 

 blood-capillary has been rea- 

 ched. The insect remains 

 motionless while it fills itself, 

 apparently withouth effort, 

 l m i h with the red warm blood of its victim. During the bite a . 

 sharp, instantaneous, burning sensation is sometimes felt, 

 owing to the saliva which the mosquito instils into the wound through the 

 end of the sheath, the conical extremity of which remains caught between 

 the edges of the wound. The insect's stomach becomes distended and the 

 blood is seen through the transparent lateral walls of its body. Several mi- 

 nutes are generally required for the completion of the operation ; as 

 long as seven in some cases which I have timed. 



It is a well-known fact that, while mosquitos are never wholly absent 



L. labrum. — m. maxillae. — H. 

 hypopharynx. — M. mandibles. 



at that time ignorant. I append therefore a reproduction of a drawing which I made 

 in 1882 or 83 of the six mouth parts of the sting. — Regarding the existence of one or 

 two tortuous tubes with striated walls, occupying the concavity of the sheath, and 

 which I considered as the excretory duct of the salivary glands, I have met with it 

 on several occasions and still believe that in the species which I am considering the 

 salivary duct may not empty itself into the tube of the hypopharynx. but runs 

 through its base lying free in the concavity of the sheath. This supposition has 

 been strengthened in my mind by a precedent which I have just read in Packard's 

 Text-Book of Entomology, p. 78 where he quotes from Meinert the following: 



"The efferent duct of the thoracic salivary glands (ductus salivalis) perforates 

 the hypopharynx, more or less near the base, that the saliva may be ejected through 

 the canal into the wound, or that it may be conducted along the labellae. Very 

 rarely the salivary duet perforating the hypopharynx, is continued in tht shápt of a free, 

 very slender tube. ' ' 



