A positive mean correlation was observed between engorged larval weight and unfed nymphal weight. Similarly, positive linear correlations were observed between engorged nymphal weight and unfed adult weight, between unfed female weight and engorged female weight and between engorged female weight and egg batch weight. Positive linear correlations were also observed between scutal length and weight of unfed adult ticks and between the duration of survival and unfed weight of adult ticks at both 43 and 85% r.h. and 28°C. At 43% r.h. and 28°C, small ticks lost water faster than larger ones. At 96% r.h. and 28°C the small ticks also gained water faster than larger ones. For the sizes tested, all the male ticks were comparable in their ability to fertilize normal females, but the smallest females were incapable of reproduction.

The distribution of Rhipicephalus appendiculatus on Setaria sphacelata flowerheads was investigated. Adult tick counts in a paddock, heavily infested with ticks for experimental purposes, revealed an aggregated distribution by deviating significantly from the expected Poisson distribution, but producing a good fit to the expected negative binomial distribution. A higher proportion of the ticks were on old dry flowerheads than on young green ones. Tests carried out in the laboratory confirmed the marked preference for old flowerheads and the aggregated pattern of distribution. The tick counts in the field revealed no sexual aggregation, though the total number of females collected was significantly higher than that of the males.