DISPOSAL OF EGGS 279 



water, close to the edge, or upon the surface of the water. Rnlay says they " lay 

 their eggs singly or in rows of 9 to 15, separated or contiguous, sometimes upon 

 the water at others upon adjoining objects very close to the water level so that 

 a slight elevation of the water will submerge them." 



The second commission to Vera Cruz state that " The eggs are sometimes laid 

 on the water, sometimes on the side of the vessel above the water line, and some- 

 times on a leaf floating on the water." 



The French commission state that the eggs are laid at the edge of the water or 

 upon it and that the latter is the commoner method. In accordance with their 

 assumption that calopus is nocturnal they assert that the eggs are generally laid 

 at night, but they admit that " numerous " captive females oviposited in the, 

 daytime. They state that oviposition extends over several hours and that the 

 time required depends upon the temperature. They found a night temperature 

 of 27° to 28° C. (81°-82° F.) with a diurnal maximum of 29° to 30° C. 

 (84°-86° F.) most favorable in hastening oviposition. Under these conditions 

 the eggs may be laid 48 hours after a blood meal, while usually the interval is 

 from three to four days. When the nocturnal temperature is between 25° and 

 27° C. (77°-81° F.) the eggs are deposited on the fourth or fifth day; when it 

 ranges between 20° and 25° C. (68°-77° F.) oviposition occurs on the sixth day 

 and sometimes not until the seventh or eighth day. When the temperature is 

 below 20° C. at night and does not rise above 22° or 23° C. (72°- 73° F.) in the 

 daytime oviposition is retarded until the temperature rises to 26° or 27° C. 

 (79°-81° F.) and sometimes it will be prevented altogether. 



Durham says of the disposition of the eggs that they " are deposited close to 

 the edge of the water, if not sometimes actually on the surface of the containing 

 basin. At any rate, they readily adhere to this surface sufficiently firmly to pre- 

 vent detachment by a stream of water ; this is probably of use when the breeding 

 places (e. g., a small tin or a roof gutter) is exposed to tropical rain." 



H. W. Henshaw, while living at Hilo, Hawaii, among other interesting ob- 

 servations made on this species, found that the females laid eggs every day 

 around his cottage in vessels prepared for them and that they invariably de- 

 posited them upon the moist sides of the containers, perhaps a sixteenth of an 

 inch above the surface, and never touching the water. Eggs removed from these 

 moist spots hatched within 30 minutes after having been placed in water 

 (in litt.). 



This undoubtedly represents the mode of oviposition under natural conditions 

 as it corresponds with that of the nearly related tree-hole inhabiting species of 

 Aedes. The impression that calopus lays its eggs upon the surface of the water 

 appears to have been gained by observations with females in captivity. It is 

 probable that the smooth sides of the glass receptacle in which such captives are 

 kept is not a suitable surface for the attachment of the eggs. 



The method of oviposition has been described by Agramonte : 



" The mosquito alighted upon the water, which was in a small beaker inside 

 the jar, with legs spread wide apart. The abdominal segments being bent 

 forwards and downwards, she dipped her whole body until the last segment 



