Illinois Natural History Survey -5— Identification Notes 3 
Dermacentor variabilis (Say) 
American dog tick, variable wood tick 
From the human viewpoint, this is the most dangerous tick in Illinois. 
It is common throughout the state and frequently attacks man and dogs. It 
can and often does carry the organism which produces Rocky Mountain spotted 
fever. The Illinois Department of Public Health has reported a total of 209 
cases and 24 deaths of Rocky Mountain spotted fever in Illinois during a re- 
cent 10 year period. 
As a precaution, those who expect to be around bushy places during the 
spring and early summer should receive a specific vaccine from their physician 
to guard against this fever. In addition it is advisable to look oneself 
over for ticks upon returning from the out-of-doors, Often these ticks wander 
for hours before biting and it is usually possible to remove them before any 
harm is done. 
Unlike D,. albipictus, variabilis is a three host tick, that is, in its 
development it leaves its host between each stage from larva to adult and 
seeks a new host for each subsequent feeding. 
Haemaphysalis leporis~palustris (Packard) 
The continental rabbit tick 
Although this tick never bites man, it is the chief transmitter of the 
tularemia organism to wild rabbits and thereby is indirectly a serious pest 
to human beings, especially hunters, It feeds mostly on rabbits but occas~ 
ionally also on song birds. In mid-winter in Illinois this tick goes into 
hibernation at which time rabbits are entirely free of the tick and of tula- 
remia. Most cases of tularemia are fatal to rabbits. Man contracts the 
disease from sick rabbits and not actually from ticks that might be still on 
the rabbit's pelt. 
Rhipicephalus sanguineus (Latreille) 
Brown dog tick 
Essentially the brown dog tick is a tropical species which is able to 
survive here only because our houses are constantly warm throughout the 
winter. 
Dogs pick up these ticks from other dogs, from houses, or from kennels, 
rarely if ever from the wild, It hardly ever bites man. In Illinois it is 
not known to transmit any disease-producing organism. 
Ixodes ticks 
The species listed below have been found in Illinois. Except for one 
species rare in our area, [xodes scapularis, they seldom bite human beings 
under normal circumstances. Ticks of this genus never have eyes nor silver- 
colored markings. 
