Abstract
The durations of the various phases of the life-history of the ixodid tickH. anatolicum anatolicumare described with particular reference to the modifying influence of temperature and relative humidity. An increase in the ambient temperature was found to decrease the length of the feeding, preoviposition, oviposition, larval and nymphal moulting periods and the egg-incubation period. The effect of change in relative humidity was less marked, the only significant effect being on the oviposition period which was protracted when the relative humidity was increased.Daily percentage water loss and longevity were found to be more or less inversely proportional. Thus at high temperatures and low relative humidities a large percentage of water was lost daily with consequent reduced life span.I wish to thank Dr R. P. Chaudhuri for providing me with the specimens ofH. anatolicum anatolicumfrom which the culture was started, and Professor D. R. Arthur for his advice and assistance. I am also grateful to the Science Research Council for the provision of a research grant.