66 



1. Note that the raft is boat-shaped, measuring 

 one-fifth to one-third inch in length, and consists of 

 two hundred to four hundred eggs. 



2. Note that the separate ova are smooth elon- 

 gated bodies, about _crjLj:o 0*8 mm. in length. Note 

 that there are no floats or other markings as in the case 

 of Anopheline ova. 



3. Note that one end of the egg is thicker and 

 blunter than the other, and that to the thicker end is 

 attached a clear transparent globular body (the micro- 

 pilar apparatus). Note that this body is readily 

 detached, often leaving a spike-like process projecting 

 from the thicker end of the ovum. 



Fig. 21. Egg Raft and Eggs of Culex 



4. Make as many observations as possible upon 

 the egg-rafts, e.g., time necessary for hatching of larvae, 

 amount of desiccation they will withstand. 



Taylor, in Havana, has made many observations on eggs. He 

 gives the following : C. pipiens, raft 200-400 eggs ; egg 0*9 by 

 O'l6 mm. C. nigritulus, raft 200-300 eggs; egg O'6 by 0-14 mm. 

 U. lowii. raft 50-75 eggs. 



5. The egg stage in C. jamaicensis lasts twelve 

 hours; in C. sollicitans, twelve hours. 



Stegomyia. Confine some gravid females of 

 Stegomyia mosquitoes. 



I. Note that in S. calopus, v. fasciata the eggs 

 are laid singly, about fifty in number, and much 

 resemble, at first sight, the ova of Anophelines. Note 

 that in others the eggs are laid in rafts (S. no to script a). 



