Frank Fenner,AC, CMG,MBE, FAA,FRS

The effect of Abate used in the control of Simulium damnosum on non‐target benthic invertebrate organisms was studied in river Oti (West Africa) in the Onchocerciasis Control Programme area. Abate was administered by aerial spraying and pre‐dosing and post‐dosing Surber samples were compared. Baetidae and Leptophlebiidae, two of the three predominating organisms were seriously affected by the Abate. Other non‐target organisms that were killed were Gomphidae, Libellulidae and Dytiscidae. Though the larvicide was toxic to other non‐target organisms, particularly Neoperla and Orthocladinae, the effect did not seem to be significant.