Stink bugs are significant pests of cotton in the southeastern USA, causing millions of dollars in control costs and crop losses each year. New methods to detect stink bug damage must be investigated in order to reduce these costs and optimize pesticide applications. One such method would be to detect the volatile organic compounds (VOCs) emitted from cotton plants damaged by stink bugs. A portable device was developed to draw VOCs from the head space of a cotton boll over carbon black-polymer composite sensors. From the response of these sensors, this device would indicate if the boll was fed upon by a stink bug or not. The device was 100% accurate in distinguishing bolls damaged by stink bugs from undamaged controls when tested under training conditions. However, the device was only 57.1% accurate in distinguishing damaged from undamaged bolls when tested 24？h after it was trained. These results indicated that this device was capable of classifying cotton as damaged or undamaged by differentiating VOCs released from undamaged or damaged bolls, but improvements in design are required to address sensitivity to fluctuations in environmental conditions. 1. Introduction Cotton containing transgenes from the bacterium Bacillus thuringiensis (Bt) subspecies kurstaki Berliner has significantly reduced the amount of foliar-applied insecticides used to control major pests of the crop, such as tobacco budworm, Heliothis virescens (F.) and bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). However, because phytophagous species of stink bugs are no longer being controlled coincidentally by applications of these insecticides, these insects have become major pests capable of causing significant economic damage to cotton [1–3]. Insecticide use for control of stink bugs increased from 0 to 4 million applications from 1995 to 2001, costing cotton producers $27 million [4]. Losses due to stink bugs in 2011 were estimated to be over $48 million in the USA, with control costs exceeding $5.3 million [3]. In order to preserve the benefits of Bt cotton and minimize the amount of insecticides needed for acceptable control, detection methods are needed that provide enhanced measures of pest density or damage, with the ultimate goal of applying pesticides only to areas that harbor insects and exceed damage thresholds. A major constraint to pest control is the difficulty associated with obtaining necessary information to make treatment decisions. Current monitoring techniques for stink bugs in cotton include field sampling with a beat cloth to determine pest densities
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