IXODIM: 495 



in time an adherent mass of eggs, which are deposited in front of 

 the tick." 



[The egg gives rise to the larval form, the so-called " seed-tick " 

 stage. At first these minute specks are pallid and soft, but they 

 soon harden and darken in colour. These larvae are six-legged and 

 crawl up grasses and various plants, and there await a passing host, 

 waving their two front legs in the air and becoming attached by this 

 means. The larval ticks feed upon the blood of the host, and when 

 replete fall to the ground, the body becoming inflated in the 

 meanwhile. These larvae may remain on the host only two days, or 

 they may remain much longer. Eventually they moult on the ground 

 and change to the nymph or pupal stage, which has four pairs of legs. 

 This pupa acts just as the larva, crawls up plants and waits to regain 

 the host. After a time the nymphs, having gorged themselves with 

 blood, fall off and remain on the ground for nearly three months ; 

 they then moult and become adult males and females. In about ten 

 days they assume their normal colour and regain the host afresh ; 

 the female gradually swells until she attains that large inflated form 

 so characteristic of ticks. The male does not swell, but nevertheless 

 feeds upon the host and fertilizes the female. 



[The act of coitus is strange : the male tick inserts its rostrum and 

 other mouth organs into the sexual orifice of the female, between the 

 base of the posterior pair of legs. The males then die and the 

 females fall to the ground and deposit the ova. There are variations 

 in the different species, of course, from those given above, which 

 apply solely to Ixodes reduvius. The larvae and nymphs seem to 

 attack most animals, but the adults mainly keep to the same host. 

 The periods in the life-cycle of ticks not only vary in the different 

 species, but in each species according to climatic conditions ; for 

 instance, in the bont tick (Amblyothma hebrceum, Koch), Lounsbury 

 has shown that the development is rapid in summer, slow in winter. 

 The period from the time that the female drops to the time she 

 commences to lay eggs varied in specimens observed by him from 

 twelve days in summer to twelve weeks in winter, and the complete 

 period from the dropping of the female to the hatching of the eggs, 

 from eleven weeks in summer to thirty-six weeks through the winter. 

 Other stages vary in a similar manner. 



[Ticks may live a long time away from the host provided they are 

 supplied with a certain amount of moisture. Mr. Wheler kept dog 

 ticks (Ixodes plumbeus) in the larval stage for ten months ; the pupae, 

 male and female, of /. reduvius for six months. 



[I have kept Ornithodorus moubata alive for eighteen months 

 without food. 



[In many species moulting takes place off the host, but in /. bovis,. 



