Sodium fluoracetate and fluoracetamide as ‘direct’ poisons for the control of rats in sewers

1. Field trials suggest that 3-monthly operations against rats in sewers using either 0·25% sodium fluoracetate or 2% fluoracetamide as a direct poison are more effective than 6-monthly treatments with 2·5% zinc phosphide or 10% arsenious oxide using the pre-baiting method. 2. In six paired trials 2% fluoracetamide gave better results (an apparent 100% clearance in five instances) than 0·25% sodium fluoracetate. 3. There is no evidence, at present, that direct poisoning treatments with 2% fluoracetamide or 0·25% sodium fluoracetate are improved by the addition of mould inhibiting substances to the bait. The work described above was made possible only by the co-operation of a large number of local authority councils and their staffs, to whom we are therefore much indebted. We wish to thank also, Mr J. D. Riley who gave considerable help during the early stages of the trials.