54 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 39 



and early stages of the chigger mite attack man persistently. 

 Ticks are larger than mites and all the species feed on warm- 

 blooded animals, including birds and mammals. Our commonest 

 Illinois species is Dermacentor variabilis (Say), fig. 61, which 

 transmits the often fatal disease called Rocky Mountain spotted 

 fever. Although this disease occurs only infrequently in Illinois, 

 hikers and others exposed to ticks should be very careful to 

 remove ticks from their clothing and bodies after every excursion 

 into the out-of-doors. 



Diplopoda This group comprises the "thousand legged 



Millipedes worms," which are not worms at all but 



members of the same general group as cray- 

 fish and insects. The millipedes have a 

 distinct head and a long body with two 

 pairs of legs on every segment. Our 

 commonest representative is the large 

 Parajulus impressus (Say), fig. 62, a 

 robust, cylindrical, reddish species com- 

 monly found in rotten logs or moist leaf 

 mold. Most species feed on decaying P ™^ 2 j^££?£*: 

 vegetable matter. A few occasionally do mon Illinois millipede. Ac- 

 considerable damage in greenhouses. tual len s th 15 inches. 



Chilopoda Elongate animals, similar in general 



Centipedes ance to the millipedes but with only 



on each body seg- 

 ment. Many species are predaceous, 

 feeding on insects and other small ani- 

 mals in rotten logs and humus. Most 

 familiar to the city dweller is the house 

 centipede, Scutigera forceps Rafinesque, 

 fig. 63 ; this is a common inhabitant of 

 dark places in houses, where it runs 

 about with incredible speed in its search 

 for small insects upon which it feeds. 

 Other species may be encountered under 



boards and stones 



Fig. 63. — Chilopoda. 

 Scutigera forceps, 

 house centipede, 

 monly 



appear- 

 one leg 



in gardens. Some 

 Illinois centipedes 

 found in woody or 

 rocky situations 



the 

 corn- 

 found in dark 

 basements. Actual 

 length of body 1.0 inch. 



