In outdoor screen cages, one and two-choice assays were conducted with gravid Cx. quinquefasciatus to assess and improve the efficacy of the Box gravid trap. Subsequently, in a field trial, a modified Box gravid trap was compared with three other gravid traps: the CDC gravid trap, the CFG gravid trap, and a novel design of a sticky gravid trap. A major disadvantage of the Box gravid trap, a relatively low trapping efficacy, was overcome with a simple modification to the trap configuration. By replacing the solid lid of the collecting tray with mosquito netting, the air velocity through the trap inlet was doubled and the quality of the resting sites for caught females was improved. As a result, the modified Box gravid trap caught and retained twice as many Cx. quinquefasciatus as its predecessor in two-choice bioassays in the screened cages and proved as effective as the commercially available CDC gravid trap in the field, but without damaging the collected specimens. Captures with the Box and CDC gravid traps were significantly greater than those of either the Counter Flow Geometry gravid trap or a sticky gravid trap.