Western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae use carbon dioxide (CO₂) to locate the roots of their hosts. This study investigated whether an encapsulated CO₂ source (CO₂-emitting capsules) is able to outcompete CO₂ gradients established by corn root respiration in the soil. Furthermore, the following two management options with the capsules were tested in semifield experiments (0.5- to 1-m² greenhouse plots): the disruption of host location and an “attract-and-kill” strategy in which larvae were lured to a soil insecticide (Tefluthrin) between the corn rows. The attract-and-kill strategy was compared with an application of Tefluthrin in the corn rows (conventional treatment) at 33 and 18% of the standard field application rate. Application of the CO₂-emitting capsules 30 cm from the plant base increased CO₂ levels near the application point for up to 20 d with a peak at day 10. Both the disruption of host location and an attract-and-kill strategy caused a slight but nonsignificant reduction in larval densities. The disruption of host location caused a 17% reduction in larval densities, whereas an attract-and-kill strategy with Tefluthrin added at 33 and 18% of the standard application rate caused a 24 and 27% reduction in larval densities, respectively. As presently formulated, the CO₂-emitting capsules, either with or without insecticide, do not provide adequate control of western corn rootworm.