I never had much luck with the traps with my tank, i had to get mine out by hand. When the lights go on in the tank, look for which rock he scurried into and move that rock (quickly!) into a bucket or similar device. Then you can wait for him to come out, or do as i did and take a turkey baster and squirt hot water into the holes in the rock. They usually come right out after that. I then filled the bucket with acetone, but if the mantis is of the more desirable variety, just acclimate it to a new tank. Good luck.