MISCELLANEOUS NOTES. 695 



back in the males but is comparatively small in the females ; this shield 

 is absent in ar°:asids, whose skin is uniformly leathery and often covered 

 with little warts and pits. The female ixodids gorge themselves with 

 blood to a much greater extent than argasid females are accustomed to 

 do, and there are various differences in habits, length of life ( much 

 greater in argasids), number of eggs laid (much greater in ixodids), 

 number of moults, relation to the host, sexual relations, and so on, as 

 well as in structural characters. 



As regards the life-cycle of ticks, there appear to be several types, varying 

 in the degree of connection of the different stages of the tick with its host 

 or hosts (i.e., the animal on which it feeds) . The number of stages in 

 argasids is usually four (though sometimes five or even six) ; larva, nymph 

 1, nymph 2, adult : in ixodids 3, larva, nymph, adult. In both the 

 larva is six-legged , the other stages eight-legged. In the relations of 

 the different species to the host, Nuttall (Parasitology^ Oct. 1911) has 

 defined five types as being of ordinary occurrence. The relations of 

 argasids are of types 1 and 2, in which the ticks feed in succession on 

 an indefinite number of hosts, making a large number of comparatively 

 small meals of blood and leaving the host when satisfied, the adult 

 females often laying a batch of eggs after each meal. The relations of 

 ixodids are of typfis B, 4 and 5 ; in type 3, each stage (larva, nymph, 

 and adult) feeds on a separate host, dropping off and moulting when full- 

 fed (je.g. Bhipicephaliis sanguineus) ; in type 4 the larva and nymph feed 

 on the same host and the adult on a second host {e.g., Hyalomma 

 cegyptium, a common Indian cattle-tick), while in type 5 (genus Boophilus 

 only) the larva, nymph, and adult stick to the same host throughout. 



In most, if not all, species the female tick, after filling up with blood, sooner 

 or later drops off the host aud lays her eggs in heaps on the ground in 

 any convenient sheltered place, and the larval ticks after hatching 

 almost always crawl up anything within reach, such as walls or grass- 

 stems, and there, with the utmost patience and tenacity of pxirpose, they 

 wait for the coming of a suitable victim, to whom they at once attach 

 themselves. Their subsequent behaviour is in accordance with one of 

 the types indicated above, and this should be borne in mind in applying 

 measures for getting rid of them : it is of little use to concentrate on 

 keeping a dog's coat clean when all the time the floor or the walls of the 

 place he inhabits may be harbouring numbers of eggs, or of larvae, 

 nymphs, or adults, which have dropped off him merely to moult and then 

 return to the charge." — Eds.]. 



No. XLIV.— ASILID OVIPOSITION. 



Time— 8 a.m., April 27th, 1911. 

 Weather — Dry and hot. 



Place — The Gooseberry plot of the vegetable garden at Pusa, the exact 

 spot selected being a dry, wrinkled, worn-out gooseberry leaf that would 

 60 



