Cone emergence cages are used to monitor populations of soil-borne insects, particularly beetles, during adult emergence. Because the cone emergence cage presumably denies access to adult beetles, including adult females, it is thought that a cone emergence cage left in place for longer than the lifecycle of the insect will have few or no beetles emerge in it. The authors tested the premise that a cone emergence cage left in place for 1 year or longer would no longer be useful as a tool to monitor the emergence of adult Phyllophaga vandinei Smyth. Our results indicate not only that cone emergence cages left in place for more than a year (P. vandinei is reported to be univoltine) are still effective at monitoring P. vandinei emergence, but often yield even more adult beetles than cone emergence cages that have been in place for a shorter time. It is not clear if this is a result of when the trap is placed or where the trap is placed. This also raises the question of whether the larvae of P. vandinei may take 1 or more years to complete development.