The efficacy of granular media CO₂ sachets used in conjunction with Center for Disease Control and Prevention (CDC) miniature light traps with light bulbs removed and modifications of bucket size and color to infusion-baited gravid traps was assessed from June through August of 2004 in Urbana, IL. The sachet packets caught significantly more mosquitoes and mosquito species compared with traps containing no CO₂ bait; however, they also caught significantly fewer mosquitoes and fewer mosquito species compared with traps baited with dry ice. Pairing CO₂-generating sachets with various dosages of octenol did not significantly increase the numbers of mosquitoes or mosquito species compared with traps baited only with sachets. When comparing modifications in the bucket size of gravid traps, the larger bucket (1,645-cm² surface area holding about 5.3 liters of infusion) caught significantly more mosquitoes compared with the smaller bucket (759-cm² surface area holding about 3.0 liters of infusion). Bucket color (green, blue, or black) did not affect the total number of mosquitoes caught.