270 MOSQUITOES OF NORTH AMERICA 



commission to Vera Cruz, without mentioning the case of Petropolis, make some 

 remarks which are significant in this connection. " We have noticed on several 

 occasions that they [Aedes calopus] are especially voracious early in the morning, 

 ahout sunrise. On several occasions a number of non-infected insects were let 

 loose in the laboratory and we observed that upon rising at sunrise they attacked 

 us viciously. It may be noted that this fact apparently explains the danger to 

 persons sleeping in an infected house and the comparative freedom from danger 

 in daylight communication with an infected town." (Yellow Fever Institute, 

 Bull. 14, p. 92.) 



LENGTH OF LIFE OF IMAGO. 



In the course of laboratory experiments, it has been necessary for medical ex- 

 perimenters to keep the females of calopus, alive for a certain length of time and 

 they have been tried with different foods, just as were the females of Anopheles 

 at an earlier date. They have been fed upon bananas and upon other fruit, upon 

 honey, and upon molasses, and in this way have been kept alive for long periods. 



The French investigators found that it was easy to keep calopus alive for two 

 months; however, beyond the fortieth day the mortality was considerable, re- 

 gardless of the method of feeding employed. This mortality was greater among 

 the males than among the females. Among the females kept in confinement 

 those that lived longest reached the age of 89, 90, 93, 97, 105 and 106 days. 

 These females had been first allowed to bite a person and were afterwards fed 

 with honey. They point out that calopus will die very quickly in a dry atmos- 

 phere. Guiteras, at Las Animas Hospital, kept five infected adults alive for 101 

 days, and one for 154 days. Goeldi has kept a female alive 102 days, feeding her 

 with blood and obtaining several deposits of eggs. He believes that the female 

 will live longer if fed only upon sweet substances. Theobald kept specimens 

 reared from the larva alive without food for two months. 



The male is much shorter lived than the female. The French commission did 

 not succeed in keeping males alive more than 50 days. Goeldi has kept the 

 males alive, feeding them upon honey, for periods of from 28 to 72 days, the 

 longest lived one escaping at the end of 72 days. Undoubtedly life was prolonged 

 in these cases beyond the normal span by withholding the opportunity for the 

 male to perform its natural function, the fertilization of the female. 



This brings us to the important question as to how long an infected yellow- 

 fever mosquito may be capable of conveying the disease. This point has not yet 

 been accurately determined. Reed and Carroll reported cases of yellow fever 

 caused by the bites of this mosquito at intervals varying from 12 to 57 days 

 after infection ; they are dangerous after the twelfth day, and thus for at least 

 45 days. Another insect under their examination lived until 71 days after 

 biting a yellow-fever patient, the dangerous interval in this case being 59 days 

 or over eight weeks. 



Reed and Carroll dismiss the fear that the infected insects are likely to be 

 carried in boxes of clothing or trunks, as groundless, since their observations 

 indicate that when mosquitoes are deprived of moisture they die within a few 



