Acarina. Acari. Mites. Ticks. 113 



palpi remain pressing around the wound and the blood is sucked 

 energetically and rapidly. The hungry tick filling itself with 

 blood may distend itself to ten times its former size, and when 

 gorged it may drop off and remains torpid, until with a new access 

 of hunger, it once more climbs on the vegetation, and lies in wait 

 for an additional victim. The ovigerous female, gorged with 

 blood, hides under some object, laj'^s her eggs and soon dies. 

 The eggs in favorable conditions hatch into hexapod larva in 

 fifteen to twenty days. The larvae may live for months without 

 food, though they are often found also on the skin of animals. 

 The nymphae are larger and octopod, but still lack sexual organs. 

 After a second moulting these form males and females. The 

 fecundated female is the largest and the most bloodthirsty of the 

 series. 



The barbed rostrum inserted in the skin holds so firmly that 

 the body of the parasite may be torn off without dislodging it. 

 If touched with a hot knife blade, or with a drop of oil so as to 

 close its stigmata it detaches itself, often rotating to the left, and 

 it is said that it may be detached by carefully turning the body to 

 the left as in extracting a screw. The skin perforated by the 

 rostrum is irritated and may become the seat of small abscesses, but 

 when extracted the lesions soon heal. A drop of benzine, kero- 

 sene, oil of turpentine, oil of tar, or other insecticide will cause 

 the tick to promptly drop off. 



Infection Through Ticks. Besides the local irritation caused 

 by all ticks, some become the bearers of other infections, such as 

 the germs of Texas fever, louping-ill, etc., which will be more 

 appropriately considered infectious diseases. 



CHARACTERISTICS OF TICKS. 



The ticks are large acarina, always visible to the naked eye, 

 even as embryos, and growing in some instances to half an inch 

 in length when mature, egg bearing and filled with blood. All 

 show the successive stages of development seen in other acarina ; 

 namely : 



Eggs, usually ovoid, with tough, leathery shell. 



Larvae, which are 6 legged and without generative pore or 

 sexual organs. 



Nymphae, half grown females, with 8 legs, but no eggs. 

 s 



