3 68 



THE MOSQUITOES 



are set vertically in the raft. The eggs of the Stegomyia are laid singly and have 

 a pearl-necklace-like fringe around them. 



The Anophelinae eggs are oval in shape with air-cell projections from either side. 

 They are laid in triangle and ribbon patterns. The markings of these air cells vary 

 and have been used for differentiation. The length of time of the egg stage varies 

 according to temperature and other conditions one to three days for Stegomyia 

 and two to four days for Anophelina. The Anophelinae are more difficult to raise 

 than Culex or Stegomyia. 



LARV.E 



There are two great classes of larvae the siphonate and the asiphonate. 

 latter are always Anophelinae. 



The 



STIGMATlC 



" UATERAL. ABDOM. HXVIRS 



ANTENNA 



MOUTH BRU 



FIG. 93. Asiphonate larva. Anopheles. 2. Siphonate larva. Stegomyia. 



The Culicinae larvae have a projecting breathing tube at the posterior extremity 

 which is called a respiratory siphon. This projects off at an angle from the axis of 

 the body, the true end of which terminates in four flap-like paddles. If you divide 

 the length of the siphon by the breath, you get what is known as the siphon index. 

 In Culex the siphon is long and slender, in Stegomyia it is short and barrel-shaped. 

 When at the surface the Culex larva has its siphon almost vertical and the body at an 

 angle of about 45. 



