The redbanded stink bug, Piezodorus guildinii Westwood (Hemiptera: Pentatomidae), has recently emerged as a serious pest of soybean in the southern United States. Field cage studies were conducted to determine the response of R2 to R6 stage soybean to P. guildinii infestation. Soybean at R2 to R6 stages was infested with zero, one, two, and four P. guildinii adults per 0.3 m for 10 d using cylindrical wire mesh cages. Plant response was measured in terms of number of flat pods, seed yield, test weight, and number of seeds per pod. Results from a 2012 study showed significant yield reduction in response to P. guildinii infestations during the R3 to R6 stages. While results from a similar 2013 study showed a significant yield reduction only when R5 and R6 stage soybean were infested. Decrease in yield was owing to the combination of reduced seed weight and increased numbers of flat pods as a result of P. guildinii infestation. In addition, a field experiment was conducted to determine if flat pods are localized to the regions of P. guildinii feeding. Adults were confined to certain portions of plants (bottom, top, and both) using specially designed cages isolating these portions of the plants. Results from this experiment showed a significantly higher percentage of flat pods on plant portions infested with P. guildinii than those kept free of P. guildinii infestation, indicating that flat pods are the result of direct P. guildinii damage and are localized to the area of P. guildinii feeding.