The infectious yeast Nematospora gossypii (= Ashbya gossypii), which is introduced into bolls by insects, was a major cause of boll rot and lint stain in Africa and Asia prior to the use of modern pesticides. However, it was noted only once approximately 20 years ago in the USA. In 2005 and 2006, feral stink bugs and plant bugs in Texas were caged over 14-day-old cotton bolls in the greenhouse to determine what pathogens were being carried and subsequently introduced into bolls by feeding. The pathogen found most frequently in both years was Nematospora gossypii with more than 50% of 200 insects introducing the pathogen into bolls. In 2006, bolls from plots sprayed and not sprayed with insecticides were collected from North Carolina, South Carolina, Georgia, and Florida. A high percentage of bug-punctured locks were infected with N. gossypii, especially in Georgia and Florida. Insecticides reduced both insect punctures and the incidence of Nematospora associated seed rot. The infectious yeast was not recovered from unpunctured locules and did not spread to adjoining locules when apparently puncture inoculated into single locules of bolls. Reactions of different cultivars are being determined and will be reported. In controlled inoculations, N. gossypii was less virulent than opportunistic bacterial isolates. However, in samples with both N. gossypii and bacteria detected, yeast concentrations were higher, indicating that it is likely a previously undetected and notable agent causing seed rot and lint staining.