168 • CIVIC BIOLOGY 



government to be $63,250,000 annually. Texas fever does 

 not become established in the North, because the tick cannot 

 survive the winter ; nevertheless it frequently appears there. 

 Northern cattle have been attacked by it as early as thirteen 

 days and as late as nmety days after the tick -bearing cattle 

 have passed tlii'ough the locality.^ Eight species of ticks have 

 been found on cattle in this country, but only 3Iarc/aropus 

 emnulatus carries the germ of Texas fever. It may be distin- 

 guished readily from the other seven by its tiny reddish-brown 

 head, contrasting with its dull yellow or even olive-brown 

 body, and by its shape and size. The body is broadly oblong, 

 sometimes reaching fifteen millimeters in length, and shows 

 irregular markino^s of yellow. Notice differences between 

 Margaropus annidatus and comparatively harmless ticks com- 

 mon on cattle (Plate lY). 



Dog tick or wood tick — Dermacentor electus. Aristotle calls 

 the wood tick, dog tormentor. \Yhoever has experienced one 

 on himself knows well the firm grip which it takes, and 

 appreciates the name. Force in removing the tick results 

 either in pulling away the body and leaving the head still 

 attached, or in carrying away a bit of fiesh with the liead. 

 The better way is to touch the tick with a drop of kerosene 

 or turpentine. It then loosens its hold and is easily removed. 



These are only a few of the mites and ticks. Frequently 



one comparatively unknown is discovered to be the cause of 



some baffling disease or a possible check to some pest. Y^our 



observations now may assist in the future. Keep a record of 



each new parasite you find — insect or arachnid ; note name 



of specimen, date, locality, host Q^lant or animal upon which 



it is found), and any facts likely to be useful. 



1 This necessitated drawing the quarantine line of 1891 across the conti- 

 nent from southern California to southern Virginia. This line has been 

 pushed southward since active tick eradication was begun in 1906, and coop- 

 eration of stockmen must eventually relieve the entire South. The problem 

 is one for serious study in all schools within or near tick-infested territory. 



