ioo8 
Journal of Agricultural Research 
Vol. XXIII, No. I* 
quite uniform, with a maximum of 86° F., a minimum of 69° and an 
average of 76°. The maximum period was obtained in a mass in a 
tumbler in which the incubation varied from 9 to 14 days. Records 
of the temperature of the room in which the jars were kept were not 
obtained, but the temperature was held rather uniformly at about 65° 
during the day. The lowest temperature observed in the room was 43 °. 
The average temperature in the insectary was 47 0 , the maximum 8o°, 
and the minimum 17 0 . The low temperature was registered on the 
second day, and several of the eggs failed to incubate; these were prob¬ 
ably the ones on the outer edge of the mass. About 43 0 may be con¬ 
sidered a fatal temperature for the eggs. 
LARVAL DEVELOPMENT 
The larvae usually begin to feed on the adult excreta within a few min¬ 
utes after emergence and develop rapidly for the first few hours. The 
excreta of the adult are apparently necessary for the development of 
the young, and these latter have never been observed to feed on any 
other material. The fatal minimum temperature is about 50° F., and 
all the larvae in an incubator died within a few hours when the temperature 
was ioo° near the tube in which they were placed. The minimum larval 
period was 14 days; the maximum, 31 days. 
PUPAL PERIOD 
The mature larvae construct cocoons of silk and dust. Apparently they 
prefer to fasten them to some firm object, as a large percentage made 
the cocoons against the side and bottom of the breeding container and 
in many cases the pupae could be observed through the glass. The pupal 
period was found to be from 9 to 19 days. 
adult development and habits 
The adults were inactive during the first few days after emergence 
and usually did not attach to a host until the fifth or eighth day. The 
females became engorged and oviposition began in from 6 to 10 days 
after attachment. Females deposited from one to four eggs per day, 
and oviposition took place during both day and night. 
The following notes were made on the act of oviposition: A well 
engorged flea was observed in the act of passing excreta mid in 18 minutes 
it was observed to be passing an egg. In 45 seconds the egg was thrown 
with considerable force and was apparently free for several seconds 
before it was thrown. While examining a flea on the head of a chicken a 
bright drop of fluid appeared; in 10 seconds an egg appeared, and in less 
than 5 seconds it was thrown with considerable force. The adult was 
observed to pass more fluid, and in 45 seconds another egg appeared and 
was thrown in less than 30 seconds. Nothing else was observed to pass 
during the next half hour. Practically all oviposition observed has 
taken place while the fleas have been attached to the host. The adults 
r emain ed attached on the host from 4 to 19 days in the same place. It 
was not determined whether they reattach after once dropping. 
Copulation has been observed to take place on the host. The fleas 
were attached on the head of the chicken about the length of the body 
apart and were ventrally by slightly laterally together. They were in 
