72 



6. Place some half -dried mud in a flat dish, 

 and put this inside a piece of mosquito netting 

 in which some Anopheltnes with ripe ovaries 

 are placed. Observe that ova are laid upon the 

 mud. 



7. Preserve the mud for forty-eight hours, 

 preventing it from becoming completely dry. 



At the end of forty-eight hours or more, 

 remove a few ova to a dry slide, and place under 

 a low power. Allow a drop of water to flow on 

 to the ova. Observe the escape, within a minute 

 or so, of the young larvae, and the fact that a cap- 

 like piece of the egg-shell is pushed off. 



8. Observe that Anopheltnes kept in a dry test 

 tube will occasionally lay their eggs on the side 

 of the tube. 



9. Note the time when the eggs were laid 

 and the time at which the larvae emerge. This 

 depends greatly on the temperature. It may take 

 two to three days. Ce. argyrotarsis, one-and-a- 

 half days (Taylor). 



10. Remove Anopheline ova on paper and 

 allow them to dry, and note that after two or 

 three days (t., 86°-96° F.) at the most, they will 

 not hatch when carefully placed on water. 



Stegomyia. — Confine some gravid females of 

 Stegomyia mosquitoes. 



1. Note that in S. fasciata the eggs are 

 laid singly, and much resemble, at first sight, the 

 ova of Anopheltnes. Note that in others the eggs 

 are laid in rafts (S. notoscripta). 



2. Note that they are irregularly oval, 

 thicker at one end than the other, and have a 

 corrugated surface in which are entangled numer- 

 ous minute air bubbles. 



