Field trials were carried out in the Richmond River districts of New South Wales from 1975 to 1978 to evaluate insecticides against corky scab in bananas which is caused by the flower thrips Thrips florum Schmutz. In 1977 /78, when thrips catches in traps were high, omethoate (0.1 % a.i.) applied at bunch emergence in summer reduced the number of fruit affected by corky scab in autumn and winter by two thirds. In 1976/7, a year of low thrips catches, no treatment had any significant effect on the level of corky scab damage. In a low incidence year the application of chemicals to reduce corky scab injury may not be economic.