AVERAGE NUMBER PER COTTONTAIL 
OLS XX 
S 
> a. sane Pe o 
Fig. 4.—Monthly average of larvae, nymphs, and adults of Haemaphysalis leporis-palustris found on rabbits examined in 
Lee County, Illinois, 1952-1954. The graph is based on data in table 2. 
Nymphs of the year appeared on Lee County rabbits 
from about the middle of August until about the middle 
of November, table 2 and fig. 4. They became most 
abundant in September and the first half of October. Like 
the larvae, the nymphs became scarce and disappeared 
from rabbits at the onset of cold weather, but, unlike 
the larvae, the nymphs commonly survived the winter in 
a state of hibernation and reappeared on rabbits in the 
spring. August 1, 1953, was our latest seasonal record 
for a nymph presumed to be of a generation started in 
the previous year. Because nymphs eventually transform 
into adults or perish, it is not surprising that a decline 
in the numbers of nymphs collected occurred in June. 
Illinois seems to be wholly in the region wherein 
continental rabbit ticks are generally absent from rab- 
bits in winter. In Lee County we did not find ticks on 
rabbits in December, January, or most weeks of Febru- 
ary, table 2 and fig. .4. In southern [Illinois we have a 
few records of limited winter activity. We have no rec- 
ords, from any part of the state, of ticks being on their 
hosts during most weeks of January, the coldest month 
of the year. On the other hand, it is probable that during 
warm winter spells some of these ticks, especially 
those in southern Illinois, may be quick to come out of 
hibernation to feed. 
If it were not for literature records of larvae sur- 
the 
possibly even Alaska (Philip 1939), we would have 
viving winter in Montana, Minnesota, Iowa, and 
suspected from our data that extremely few larvae of 
the continental rabbit tick can overwinter in northern 
