26 Mosquitoes 



will produce larvae and yet, if the whole unbroken 

 mass be secured under water, no larvae will emerge? 



Many people imagine that mosquitoes are in the 

 habit of breeding in wet grass, from the frequency 

 with which adults are found there, but this notion is 

 erroneous. The ova, so far as Dr. Dupree and the 

 writer have observed, are always deposited in water, 

 although accurate observers have seen eggs of the 

 salt-marsh species commonly laid in wet mud, and 

 there is no doubt that, among the species whose 

 eggs resist drying, this habit is variable. Since rafts 

 will not survive over four hours' desiccation, accord- 

 ing to Dr. Dupree's experiments, the writer does 

 not believe these are ever placed elsewhere than on 

 water. Mr. F. Knab 1 says that he has found the boats 

 of territans above the water level in a barrel, and 

 also under a tussock. The observation is no doubt 

 accurate, but the position of the rafts may be ac- 

 counted for by removal of water and film tension. 



The time for oviposition is, as a rule, late at night 

 or early in the morning. We have seen 5. calopus 

 and C. rcstuans laying late in the afternoon of a dark 

 da)'. The insect may sit upon the water or at its 

 edge. Single eggs, except those of Anopheles, soon 

 sink, as a rule. Dr. Dupree found agitation to be a 

 great factor in the hatching of this form of ova. 

 The eggs, lying at rest on the bottom, develop the 

 embryos rapidly, usually (in warm weather) in from 

 twenty-four to forty-eight hours. If left undisturbed, 

 they may remain unhatched for over a year, as with 

 5. ealopus and J. posticata. But he found that after 



^Journ. N. Y. Ent. Soc, vol. xii , no. 4, Dec, 1904. 



