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This paper records the identities of 558 ixodid ticks feeding on 194 humans in South Africa. These ticks belonged to 20 species in six genera and those most frequently encountered were AmblYomma hebraeum, Haemaphysalis leachi, Hyalomma marginatum rufipes, Hyalomma truncatum, Rhipicephalus appendiculatus, Rhipicephalus gertrudae and Rhipicephalus simus. With the exception of the larvae of R. appendiculatus, the incidents of these ticks feeding on humans correlated well with their seasonal occurrences on preferred hosts. Ticks were also collected at monthly intervals, for 14 consecutive months, from the clothing of a game-guard providing protection for field-workers engaged in the collection, by means of flannel strips, of free-living ticks from the vegetation of four localities in the southern region of the Kruger National Park. In addition, with the exception of 3 months when the particular worker was absent, ticks that fed on one of the field-workers were collected over the same 14-month period. A total of 54,429 free-living ticks belonging to 14 species and six genera were collected from the vegetation at the four localities during this time and 3751 ticks belonging to 11 species and six genera from the clothing of the game-guard. The larvae of A. hebraeum and Boophilus decoloratus were the most numerous of the immature ticks, and H. leachi and R. simus of the adults on both the vegetation and the guard's clothing. Ticks fed on the field-worker on six occasions and 14 were collected, all of which were A. hebraeum larvae.

Numerically equal groups of between five and ten young Merino and Dorper sheep were artificially infested with sheep scab mites, Psoroptes ovis. Separate groups of sheep were infested during the early winter of two successive years as well as during the early summer of the second year. Lesion growth was measured at two-weekly intervals for a period of six weeks during the first winter and for eight weeks during the second winter and in the summer. The rate of lesion growth and mean lesion size on Merino sheep was significantly greater than that on Dorper sheep at each two-weekly recording during the winter of both years. The rate of growth of the lesions did not differ significantly between the two sheep breeds during summer, although, with the exception of eight weeks post-infestation, the mean lesion size on Merino sheep was significantly larger than that on Dorper sheep at each assessment.

The effect of feeding immature Karoo paralysis ticks (Ixodes rubicundus) on the resting metabolic rate (RMR) of their principal natural host, the rock elephant shrew (Elephantulus myurus), was investigated under laboratory conditions. The elephant shrews were artificially infested with numbers of ticks simulating natural burdens. The RMR of the elephant shrews was quantified by measuring the oxygen consumption in an open through-flow system. The RMR of hosts infested only with larvae did not differ from that of the control group. Those infested with nymphs, or nymphs and larvae, had significantly lower RMR's compared to the control animals. There were no signs of paralysis in any of the infested hosts.