294 



NOTES ON THE BIOLOGY OF IXODES 



By G. H. F. NUTTALL. 



Introductory 294 



Outline of the life-history in Ixodes 295 



Ixodes ricinus 296 



Duration of parasitism upon the host .... 298 



Site of attachment upon the host .... 299 

 The time required for metamorphosis to take place in the 



different stages 300 



Longevity 301 



Time required to complete the life-cycle .... 301 



The influence of season and local conditions . . . 303 



Copulation 303 



Oviposition 308 



Belation to disease 312 



Eedwater in cattle — Note re Karyolysus . . . 312 



Effects of bite on man and animals .... 313 



Penetration beneath the skin 314 



Ixodes ricinus var. scapularis ....... 315 



Ixodes anguslus .......... 315 



Ixodes pilosus 316 



Ixodes canisuga .......... 316 



Ixodes pntiis .......... 317 



Appendix I. On the process of copulation in Ornithodorus 



moubata 318 



Appendix II. On the adaptation of Ticks to the habits of 



their hosts 324 



Introductory. 



Of the 51 species which we recognize as valid, there are but two 

 about which we are still somewhat in doubt, namely, bicornis, which 

 may be identical with diver sifossus, and nigricans, which may be but a 

 variety of ricinus. This leaves 49 well-established species. Of these, 

 the life-histories of but 8 are known in so far as both sexes, the nymphs 

 and larvae have been recorded. Only a few of the latter have actually 

 been raised experimentally through some of their stages. Partial 

 raising experiments have been carried out in Cambridge with ricinus, 



