146 INSECTS AND MAN 



During this time they increase in length from one-thirty- 

 seventh to one-eighteenth of an inch and change in colour 

 to slate grey. After engorgement they drop from their host 

 and seek some hiding place in the undergrowth where they 

 can continue their development. Repletion has rendered 

 them less active, and so they remain more or less inert 

 till, at the end of from a week to three weeks they shed 

 their skins and appear in a new guise, as eight-legged 

 nymphs, and hungry withal. As more blood is necessary 

 for further development, the nymphs, now about one- 

 seventeenth of an inch in length, emerge from their hiding 

 places and once more become attached to some hapless 

 mammal, for a period of three to nine days, during which 

 time they feed on its blood, and increase in length to about 

 one-sixth of an inch. After feeding, the nymphs fall to 

 the ground, hide once more and become inactive ; their 

 sexual organs are formed during this period, and, after 

 a second moult, they appear as mature male and female 

 ticks. 



At first the adults of both sexes are somewhat inactive 

 and rather soft in texture ; almost similar in size, they may 

 be distinguished by the fact that the male has a plate or 

 shield, decorated with a complicated pattern of white 

 stripes, entirely covering his back. The female too has a 

 shield, but behind it is her soft, elastic, usually wrinkled, 

 reddish-brown body. Before the adults can proceed to the 

 business of increasing their kind another substantial meal 

 of blood is a necessity for both sexes : this is usually derived 

 from some large domestic animal. On cattle, the dewlap 

 and between the fore and hind legs, and on horses, between 

 the fore and hind legs, and sometimes on the mane, are the 

 most favoured spots. 



The change of hosts from small mammals, such as 

 squirrels, in the larval and nymphal stages to the larger 

 domestic animals in the adult stage is a firmly fixed habit 

 of this tick, and it is due, no doubt, to the fact that the 



