Helicoverpa spp are considered the most damaging insect pests of cotton in Australia and consequently have attracted considerable research attention. Problems with insecticide resistance and possible environmental damage associated with excessive insecticide use has led to concerted efforts to reduce spraying in cotton. Integrated Pest Management(IPM) methods and area wide management have emerged as new tactics and are underpinned by decision support systems, including CottonLOGIC. However, despite the myriad of factors to be taken into consideration before spraying, the most important remains the &quote;pest threshold&quote;, as measured by crop scouting. In the case on Inguard cotton, the established threshold for Helicoverpa is a total of 2 larvae/m row in all crop growth phases(Anon. 2002). Early experiments with INGARD at Kununurra raised concerns that the fixed threshold of 2 larvae/m may not be appropriate for the unusual winter growing environment in the Kimberley. The concerns were twofold, firstly because the &quote;reverse&quote; growing season meant that cotton growth was rapid in high temperatures at the beginning and end of the season but slow during boll development in mid-season, and secondly, that extensive periods of &quote;sub-threshold damage were often observed. To test the validity of established Helicoverpa thresholds in the winter system, a series of field trials were conducted between 1998 and 2001 with the aim of developing a more dynamic and responsive threshold to better reflect the growth stage of the crop and the impact of insect damage