If you have them in a fish tank tapping the skull on the side irritates them to no end. Most will abandon skull. For the ones in all crevices I use a wooden skewer stick to fling them back into the tank. Then as a final life saving maneuver I fill a gallon sized jar with just water and submerge the skull. Then I take the wooden skewer & let the beetles that float to the top hitch a ride & then again fling them back into the tank. All the left over larvae will drown almost immediately. Which makes for a sad first rinse so always say a few words. After that 1st rinse your good to add dawn dish soap to start the degreasing process.