The control of leatherjackets, Tipula paludosa Meig., in grassland by early application of insecticide

To determine whether leatherjackets might be controlled by application of a pesticide in summer, before oviposition by crane flies, chlorpyrifos was applied to perennial ryegrass (Lolium perenne) swards on dates from July to September in anticipation of leatherjacket infestation. Subsequent winter population estimates showed that leatherjacket numbers had been reduced by at least 85% by 0·72 kg chlorpyrifos ha-1 applied on 13 July, and by 0·60 kg ha-1 applied on 3 August or later. The significance of leatherjacket control by pesticide application on these dates is discussed in relation to previously recorded effects of pesticide treatment on other known pests. It is concluded that control of all common arthropod pests of proven significance in established grassland may be achieved with one application of pesticide.