A mud-sampling technique for the study of the ecology of aquatic snails, and its use in the evaluation of the efficacy of molluscicides in field trials.

The author describes a sampling technique suitable for estimating the population densities of African aquatic snails in the field by the removal of a plug of mud and its subsequent detailed examination. This device has been used in field trials with the molluscicides ICI 24223 and Bayer 73. Estimates of percentage kills were based on counts of live and dead snails in each mud sample before and after molluscicide treatment. Statistical analysis of these counts suggests that most snails killed by the molluscicides were subsequently recovered, thus providing some confirmatory evidence of the validity of these estimates.