278 MOSQUITOES OF NORTH AMERICA 



during an interval of 15 days or more. All 36 of the eggs deposited proved 

 fertile and had produced larvae five days later. Goeldi supposed that in this ex- 

 ceptional case oviposition resulted from the effect of a previous blood meal. In 

 another experiment Goeldi fed a female exclusively with honey for 75 days -with- 

 out obtaining eggs ; she was then fed blood for 20 days. On the 20th day of the 

 blood diet a single egg appeared and six days later, or 102 days after the experi- 

 ment was begun, 85 eggs were deposited. Goeldi calls this the first batch of eggs 

 but it would seem as if there had been some oversight, for, 13 days after the 

 female was put on a blood diet a larva was found in the breeding cage. Goeldi 

 tried to determine the comparative effect of guinea-pig blood on oviposition. 

 Of two females fed with guinea-pig blood one laid seven eggs three days after 

 the first meal ; the second female was given another ration and four days later 

 had laid no eggs. Goeldi remarks that these data are too insufficient to be con- 

 clusive, but he expresses the belief that it will be found that human blood is 

 much more effective than the blood of the guinea pig. 



The French investigators pointed out that the ability of calopus to transmit 

 yellow fever depends upon the fact that it needs several blood meals to develop 

 all its eggs. The female continues to bite after having oviposited and, without 

 being fertilized again, deposits more fertile eggs, and this may be repeated a 

 number of times. They found that in captivity a single blood meal between 

 ovipositions was effective. They state that in freedom calopus, after having 

 deposited eggs, would often bite every 24 hours and sometimes even several times 

 within that period, and they call attention to the significance of these frequent 

 bites in the transmission of yellow fever. Among the females which have de- 

 posited eggs once there are some which survive a long time, and, while con- 

 tinuing to suck blood, do not lay more eggs. This, they think, is due to the fact 

 that the supply of spermatozoa in the receptacula seminis has been exhausted. 

 These females, in the opinion of the French investigators, are the most dan- 

 gerous on account of the probability of their living a long time and biting many 

 persons. 



It has already been shown that calopus will only feed upon blood obtained by 

 piercing the skin. Otto and Neumann claim that they were able to feed female 

 calopus with a mixture of blood and salt solution placed upon cotton. The mos- 

 quitoes sucked the blood from the cotton without hesitation ; afterwards eggs 

 were laid in the normal manner and larvae hatched from these, but it appeared 

 that these larvae lacked the usual vitality. 



The French investigators made feeding experiments with human blood serum, 

 with red blood corpuscles separted by centrifugal action, and with blood clots, 

 and from none of the females so fed were they able to obtain eggs. When these 

 same females were afterwards allowed to suck blood they laid eggs. They con- 

 clude from this that calopus must have fresh blood in order to lay eggs, 



OVIPOSITION. 



Aedes calopus deposits its eggs separately in several lots, the separate lots being 

 disposed of at intervals of several days or more. The eggs may be laid near the 



