LOUPING-ILL. 



433 



The Larva. When first hatched out from the eggs, which are sup- 

 posed to be laid at the roots of coarse herbage, the young ticks are 

 white and soft, but soon gain strength. Provided the weather is favour- 

 able, they climb up the stems, and, holding by their two posterior pairs 

 of legs, await the passing of a host, employing their two front legs as 

 insects use their antennae. 



In this, as in other " free living " stages of their existence, the young 

 larvae show great activity, attaching themselves and clinging tenaciously 

 to any moving object. They appear to be more numerous on the rank 

 rushes growing in damp, undrained places. 



On finding a host, larvae attach themselves by the rostrum, and remain 

 there for about two days, by which time they are distended, black and 

 globular. At this time they are easily detached 

 from the host, and have lost their activity and 

 clinging habits. 



The Pupa. The possession of eight legs dis- 

 tinguishes the pupa easily from the larva. The 

 extra pair are placed behind the others. After 

 the metamorphosis, the pupa takes up its posi- 

 tion on the stalks of herbage, just as the larva 

 had done, for another chance of attachment to 

 a host. But whereas adult grass ticks seem to 

 confine themselves mostly to sheep, cattle, and 

 deer, the larvae and pupae attach themselves 

 very readily to various hosts, such as horses, 

 dogs, and even human beings. After about 

 four days the pupa is again replete with blood, 

 black and opaque, and again drops to the 

 ground to undergo its second and final change. 



Adults. On reaching the adult age, both males and females again 

 wait on herbage for a passing host. At this time, as well as after dis- 

 tension of the female on the host, an action which appears to be sexual 

 intercourse freely takes place, even in confinement. On the host the 

 females gradually distend (Fig. 202) , and in the course of so doing vary 

 much in colour and appearance. When fully replete, the female Ixodes 

 redaviiis becomes globular and black. One taken in this condition on 

 April loth commenced to lay on May 12th, and a few others taken at 

 the same time commenced shortly afterwards. 



Grass ticks never remain on the host to undergo metamorphosis or to 

 lay eggs. They must therefore during their cycle of existence contrive 

 to find a fresh host no fewer than three times. 



In an article published in the Transactions of the Highland and 

 Ag. Soc. for 1902 ^Ir. Wheeler draws attention to the close points of 



D.C. F F 



Fig. 202.— Partially dis- 

 tended female. The 

 dotted white line repre- 

 sents the size of the 

 tick before distension. 



