An actuator assembly is disclosed which can dispense chemicals, such as insect control ingredients, from an aerosol container. The actuator assembly is mountable to the aerosol container and includes a burstable barrier and an extrudable (e.g. paste) plug. Upon initial activation, the pressure from inside of the container presses the burstable barrier which in turn presses the paste plug to cause at least a portion of the plug to move to a position where it is visible and provides a cue that a delay period has started. The device can be manually activated, but is designed so that thereafter it does not need to be manually held open. The user has time to leave the room before spraying begins, and does not need to be present in the room before spraying has finished.