On the Period of Survival of the Egg, Larva, and First Nymph Stages of the Argasid Tick Ornithodorus moubata, Murray, at different relative Humidities

Abstract

The longevity and development of the eggs of Ornithodorus moubata, Murray, at different relative humidities between 6·2 per cent. and 80 per cent. were investigated. It was found that:—(1) All stages investigated, i.e., egg, larva and 1st nymph, survived for a much longer period at high humidities than at low. The longevity snowed a steady gradation through the range of humidities used.(2) Even at very low humidities a sufficient proportion of eggs developed to the 1st nymph stage to carry on the race.(3) The 1st nymph is much more resistant to desiccation than the earlier stages.This result does not agree with opinions expressed as the result of field observations, or with the only previous laboratory experiment it was possible to trace. Reasons for both these disagreements are suggested.