A RECENT trend in the control of insects has been the development of pest management systems whereby combinations of control methods, applied to one or more stages of the life cycle, increase efficiency and optimise effectiveness of individual methods. The potential of an integrated programme involving the release of sterile insects in combination with other control methods was discussed by Knipling1. He pointed out that two properly chosen and implemented systems might be regarded as synergistic in effect. Kunz and Eschle2 have proposed an integrated programme against the horn fly, Haemotobia irritans (L.), and they have suppressed the reproduction of a semi-isolated population 98% by releasing sterilised horn flies3. In the spring of 1973, we began a pilot test on the island of Molokai, Hawaii. The objective was to develop a control system whereby a natural population of horn flies could be suppressed by chemical means and then eradicated through the release of sterile flies.