272 MOSQUITOES OF NORTH AMERICA 



Otto and Neumann have made experiments on the resistance of the adult 

 Aedes calopus to cold. These were made in Germany, with imagos bred in con- 

 finement. When calopus were placed outside the window with the temperature 

 at the fieezing point they died very quickly. When exposed to a temperature of 

 4° C. (39° F.) for one hour and then returned to the warm room they could 

 still be revived, but longer exposure killed them. However, calopus can survive 

 cool temperatures for a considerable time. Carter states that " Guiteras placed 

 thirty-three mosquitoes in an ice-box at 46.5° to 50° F., without food or water; 

 three of them survived to the eighty-seventh day, when they were eaten by ants." 

 Otto and Neumann, in a similar experiment, with a constant temperature of 

 7° to 9° C. (45.5°-48° F.) kept calopus alive to the eighty-second day. In this 

 experiment they employed 25 male and 25 female mosquitoes; they were fed 

 with sugar, honey and water, and part of the females had sucked blood. In a 

 short time the insects became stiff and only moved very slowly; they nearly 

 always sat en the bottom cf the jar, as if they could no longer retain their hold 

 on the glass sides. After three days four of the males died and none of the re- 

 maining 21 males survived the fifteenth day. O21 the contrar}' but very few of 

 the females died in the first two weeks and after 30 days about half of them still 

 remained alive; on the fiftieth day three were alive; after 61 days but two, and 

 after 71 days only one remained. 



THE BITING OF CADAVERS. 



An interesting observation made by Eosenau, Francis and Goldberger (Eeport 

 of Working Party No. 2) indicates that the yellow-fever mosquito may bite a 

 cadaver, and, if on a dependent portion, can draw blood. The two observations 

 made on this point were as follows : 



" Narciso Nadal (Case XX). A number of Stegomyice were applied twelve 

 hours after death, only one of which apparently obtained blood. 



" Trinidad Martinez (Case XXII) . A number of female Stegomyice fasciatce 

 were applied one-half hour after death, and three insects succeeded in feeding 

 with blood." 



These authors point out that, as the work of the French commission has shown 

 that the blood of yellow-fever patients is not infective after the third day, the 

 danger of the carriage of infection by mosquitoes which have fed upon cadavers 

 must be very remote. The only chance of infection from such a source would 

 be in the case of the death of the patient within the first three days. 



DISTANCE OF FUGHT. 



The distance of flight of the adult is a very important question. Calopus 

 seems to be a strong flier, as is evidenced by a series of experiments carried on 

 by Goeldi on the effect of a strong current of wind between two open windows, 

 or by air currents produced by a mechanical ventilator. He found that calopus 

 pays absolutely no attention to such currents, continuing its evolutions about 

 him and stinging precisely as though the air current made no difference to it. 

 This indicates that calopus would not easily be carried involuntarily by the 

 wind. Opposed to these assertions of Goeldi are the observations of Otto and 



