and Glen C. Sanderson, the latter employed jointly by 
the [llinois Department of Conservation and the Illinois 
Natural 
with those gathered from many other areas by Survey 
History Survey. These collections, together 
staff members, were compared with the data obtained 
from Lee County in northern Illinois to secure informa- 
tion on the differences in the seasonal behavior of 
rabbit ectoparasites within the various climatic zones 
of Illinois. Illinois, a long state, extends about 380 
miles from north to south and embraces several climatic 
and life zones. 
Cottontails in Illinois are the normal hosts to at 
least seven species of facultative or obligate ectopara- 
sites, exclusive of chiggers and other small mites. In- 
frequently, perhaps accidentally, rabbits of Illinois may 
acquire other species of ticks and fleas that regularly 
feed on other mammals, such as ground squirrels, mice, 
and moles, but these ectoparasites do not usually per- 
sist on rabbits. 
Rabbits in the western part of North America are 
hosts to several more, most of them different, species 
of ectoparasites than are rabbits in the eastern part, 
table 1. Often where one species of ectoparasite drops 
out at the edge of its range, another biologically equiv- 
alent species takes over and continues into the adja- 
cent geographical range. There is a sudden change in 
the kinds of species of ectoparasites on rabbits at 
about the 100th meridian. Cottontails in Illinois are 
infested by every rabbit ectoparasite known. east of the 
100th meridian except the flea //oplopsyllus (Euhoplo- 
psyllus) glacialis affinis (Baker). To date, no speci- 
mens of affinis have been taken in Lee County or else- 
where in Illinois. 
TICKS 
Haemaphysalis leporis-palustris (Packard); conti- 
nental rabbit tick, rabbit tick; fig. 2. When ranked ac- 
cording to numbers of individuals collected within a 
period of a year, the continental rabbit tick stands as 
the principal ectoparasite of cottontails in Illinois. 
This tick is also apparently the chief carrier from rabbit 
to rabbit of the organism, Pasteurella tularensis, that 
produces tularemia, a disease which is invariably fatal 
to rabbits (Green 1939). 
Although the continental rabbit tick is common over 
much of North America and all of Illinois, fig. 3, and is 
collected frequently by biologists, many aspects of its 
life history are poorly known. 
We found and others have reported that individuals 
of this tick feed mostly on the rabbit’s head, particularly 
on and in the ears, on the back of the neck, and some- 
times around the eyes and nose and under the chin. 
Hooker et al.(1912) were among the first to publish 
detailed biological information on this tick. According 
to their findings in Texas, ‘‘The three stages of the 
rabbit tick have been taken from hosts in nature during 
all seasons of the year.’’ 
According to a number of authors, the continental 
rabbit tick in areas north of Texas, specifically in Okla- 
Table 1.—Distribution of the common ectoparasites of rabbits in the United States, exclusive of chiggers, 
small mites, and nest inquilines. 
Species Found East of 
Group 100th Meridian 
Haemaphysalis leporis-palustris 
Ixodes dentatus 
Haemaphysalis leporis-palustris 
Ixodes spinipalpis 
Species Found West of 100th Meridian 
Haemaphysalis leporis-palustris 
Ixodes neotomae 
Hoplopsyllus glacialis affinis 
Ticks Dermacentor variabilis Dermacentor andersoni Dermacentor parumapertus 
Otobius lagophilus Ornithodoros turicata 
Cediopsylla simplex Cediopsylla inaequalis Cediopsylla inaequalis 
Odontopsyllus multispinosus Odontopsyllus dentatus Odontopsyllus dentatus 
Fleas Hoplopsyllus glacialis affinis Hoplopsyllus glacialis affinis 
(Apparently rare east of Missis- Hoplopsyllus foxi 
sippi River; taken from imported 
Kansas cottontails in New Jersey, 
Burbutis & Mangold 1956) 
+— 
Cuterebra buccata Cuterebra leporivora Cutere bra leporivora 
Bot Cuterebra horripilum Cuterebra lepusculi Cuterebra lepusculi 
Flies Cuterebra cuniculi 
Lice 
Haemodipsus setoni 
Haemodipsus setoni 
