G. H. F. Nutt ALL 
447 
Summary. 
Rhipicephalus bursa requires two hosts upon which to feed (a) in 
the larval and nymphal stages and (h) as an adult. The tick is, partly 
for this reason, one of the easiest to rear. We have not attempted to 
rear it on other hosts than sheep and cattle. The larvae and adults 
feed readily a few days after they emerge, and after a fast of six months 
or more. Th e length of time the tich remains upon the host varies according 
to its seat of attachment and its consequent access to a supply of blood; 
under the most favourable conditions the larvae are fully gorged in 
about 8 days; they undergo metamorphosis whilst still attached to the 
host and the nymphs emerge about the 12th day. The nymphs, without 
altering their position upon the host, reattach themselves and proceed 
to feed, dropping off the host about 10 days later. The period of 
parasitism, reckoned from the time the larvae begin to feed until the 
replete nymphs abandon the host, lasts 19-20 days (minimum), in most 
cases 22-23 days, no doubt it may last longer if conditions are unfavour¬ 
able. Females feed for 4-12 days (mostly 8 days) upon the host. 
Males remain attached for an indefinite period after the replete and 
fecundated females have dropped to the ground. When both sexes, 
or females alone, are placed upon the host, they attach themselves 
readily. In the absence of males the females feed very slowly, remaining 
attached for 15-91 days and never growing as replete as those which 
have been fecundated^. Copulation takes place upon the host. Whereas 
Motas states that the proportion of the sexes to each other is barely 
1 d to 3 ?, we find, as the result of our extensive rearing experiments, 
that no such disproportion exists: the adults of the 1st generation 
raised in the laboratory numbered 1817 of which 824 were d and 993 ?; 
the adults of the 3rd generation numbered 3363 of which 1696 were 
d and 1667 $; the sexes are therefore represented by nearly equal 
numbers. MetamorjFiosis from egg to larva lasts 43-47 days at 24° C., 
67-76 days at 18° C.; from larva to nymph (upon the host) 4 or more 
days; from nymph to adult 12-14 days at 30° C., about 103 days at 
19° C. The loss of life during metamorphosis from nymph to adult 
appears to be slight, thus of 3463 nymphs which had gorged themselves 
only 100 failed to reach maturity. Oviposition^ commences 8-17 days 
(usually 8-11 days) after the gorged and fecundated female has aban¬ 
doned the host and (when the ticks are maintained at ca. 18-24° C.) 
* See the paper whicli follows (p. 457). 
