If searching doesn’t turn up your missing snake, it’s time to set a trap. You can set “sound traps” along the walls — crumble plastic bags and put them on the floor along the exposed walls and between furniture. As soon as it’s dark, turn off all the lights and sit quietly with a flashlight. Listen for your snake on the move — it may take a half hour for him to start exploring. Once you hear the noise of the snake moving past the plastic bags, click on the flashlight and nab him!
You can also sprinkle a strip of flour or cornstarch across your doorways. This won’t catch the snake, but it will tell you if he’s moving from room to room — as he slithers around, he’ll leave flour trails in his wake!
If you still can’t catch your snake-at-large, you can always let hunger be your lure. Place some pre-killed food (like a mouse) in a large plastic bottle or a small cage. Poke holes in the bottle so the scent can escape. Your snake may come out of hiding for a snack, and be too fat to fit back through the neck of the bottle or between the bars of the cage.
The best thing you can do to prevent an escape is make sure your cage or tank is completely secure! Don’t rig up some crazy contraption with screens and bricks; an industrious snake can take advantage of the smallest gap and make a break for it. Snakes are flexible and squishy! A space you may think is too small may be just the right size for an escape.
Make sure the room your snake enclosure is in is secure, too! Patch up any holes in the walls, unless you want your snake escaping that way. Close the gap under the door, unless you want your snake making its way into the rest of the house, making your search that much more difficult.