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Chapter XXXII 
Yellow Fever 
The cause of the disease is unknown. The following 
facts have been established :—- 
(1) Stegomyia calopus that has fed on a patient 
during the first three days of the fever can transmit the 
disease twelve days later, but not before. This period 
is longer if the temperature of the air is low ( e.g . 8o° F.). 
(2) The incubation period in the patient is 
two to six days. 
Stegomyia calopus. —A black and white mosquito. 
Proboscis unbanded. Thorax ornamented with a 
curved silvery line on each side and two median 
parallel lines, giving the characteristic lyre pattern. 
Hind tarsi basally banded with white, the last tarsus 
being all white (Plate VI). 
Habits .—According to some observers this mos¬ 
quito, after the first week of life, bites only at night 
(5 p.m. to 7 a.m.), but this is doubtful, though probably 
feeding generally takes place at night. 
Breeding Places. —Breeds especially in £ domestic ’ 
collections of water in pots, pans, barrels, jars, tins, 
cisterns, boats, troughs, etc., etc., but not commonly 
in natural puddles. 
Egg-laying. — Occurs chiefly at night, sixty to 
seventy being laid. They measure 550 by 160/^ (p. 67). 
The eggs will hatch after being kept ‘ dry ’ for some 
months. Hibernation is probably mainly by the eggs. 
