The southern green stink bug, Nezara viridula (L.), utilizes stylets while feeding to pierce the wall of a boll of cotton, Gossypium hirsutum L., and can inoculate disease-causing pathogens into developing green bolls. Detection of diseased bolls is difficult because the surface of the carpel wall frequently lacks apparent macroscopic evidence of insect feeding regardless of infection; blisters on the interior surface of the carpel wall are commonly masked by darkened necrotic tissue. The objectives of this study were to characterize microscopic evidence of feeding by laboratory-reared southern green stink bugs on greenhouse-grown cotton bolls and to use these findings to aid in detection of feeding evidence by piercing-sucking insects on field-collected bolls from four southeastern states. Microscopic analyses of greenhouse-reared bolls fed upon by southern green stink bug (n = 40) yielded definitive characteristics and imagery of feeding evidence. Salivary flanges on the exterior surface of the boll and blisters at the feeding site on the interior surface of the carpel wall were characteristic of feeding by southern green stink bug. Also, salivary flanges were associated with all external puncture wounds on the boll wall. These characteristics were used as the baseline to detect feeding by feral piercing-sucking pests on field-grown bolls during the 2008 and 2009 production seasons. Injury characteristics from field-grown bolls were comparable to characteristics observed in greenhouse-reared bolls after feeding by southern green stink bug. A few field-collected bolls (5%; n = 160) possessed discolored seeds and exhibited evidence of boll feeding externally but lacked blisters on the interior surface of the carpel wall, thus suggesting an incomplete breach of the interior carpel wall. Callus tissue, colloquially termed a ‘wart,’ on the interior surface of the boll carpel wall is typically associated with feeding by stink bugs but was not detected in bolls grown in a greenhouse and was only sporadically detected in bolls collected from the field. When present, callus tissue was always associated with an external puncture. This is the first study to unequivocally illustrate microscopic characteristics associated with feeding damage by southern green stink bug on cotton bolls. Findings are discussed in relation to evidence of feeding by insects in field-collected bolls of unknown age and history.