ABSTRACT.1A comparison was made of the insect fauna on pairedTerminalia sericea, Burkea africanaandOchna pulchratrees; one tree in each pair was treated with Formex® to exclude ants from the canopy, and the other was designated the control.2Treatment with Formex banding to exclude ants did not influence plant phenology.3Pyrethrum knockdown samples from control trees had generally more insect individuals and insect species than samples from trees where ants were excluded.4Formex‐treated trees had significantly less homopterous individuals and species than the control trees.5With the exception of ants and Homoptera, there was no difference in the insect guild composition and dominance ranking of various insect taxa, sampled by pyrethrum knockdown, between the control and Formex‐treated trees.6T.sericeahad significantly greater populations of both sessile and mobile Homoptera on the control trees than on the Formex‐treated trees. A similar trend could be seen onB.africana.There were significantly more sessile homopterans on the control trees ofO.pulchrathan on the Formex‐treated trees. Low numbers of mobile Homoptera were recorded on both control and Formex‐treatedO.pulchratrees, and numbers on control trees were fewer in comparison to numbers of mobile Homoptera on controlT.sericeaandB.africanatrees.7It is concluded that the ants have similar effects on the insect communities of trees in a natural, undisturbed savanna as has been demonstrated on trees in agro‐ecosystems, and on plants that are structurally adapted for mutualistic associations with ants.8Although slight, leaf damage by some leaf‐feeding insects was greater on trees where ants had been excluded than on control trees that supported foraging a