At 1.5 ft there is almost no crack or crevice too small to hold a snake. As related in the previous posts, escapees are where you find them. Bookcases, upholstered furniture, dressers, closets, rugs, vents, door jambs, elecrical appliances, fixtures, wainscotting, boxes, bags, shoes, pants pockets, water heaters, stoves, furnaces, fridges,...well the list is just endless.
Be aware that even if you search diligently, every conceivable hidy hole, your fugitive may be moving about while you search, dodging out of and into hiding spots while your attention is focused elsewhere. You should check likely spots over and over.
WATCH YOUR CAT! Cats are excellent at finding snakes. I have had more then one runner apprehended this way. Unfortunately they also will kill them. However, most domestic cats probably wont eat a snake, since it tastes/smells nothing like their regular food, esp. indoor cats who have never encoutered one before.
Pick likely spots (dark secure and warm) to put out hide boxes, food, and water. Check them fairly frequently, but not so often that the commotion might scare him off.
Look at your floor and wall junctions carefully - are there gaps? Crevices? Places where there might be tiny tight spots they can just squeeze into? Baby snakes love these - the tighter the better.
If you live in an apt., you might consider warning your neighbors - snakes can turn up in the most surprising locations. But don't go overboard - some folks really don't like snakes, and could get you in hot water with management.
Above all, don't give up - your snake may turn up weeks or months later, none the worse for wear.
Good Luck,
John D.
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I am so not lesdysxic!
0.1 Creamsicle Cornsake "Yolanda"
1.0 Bairds Ratsnake "Steely Dan"
0.1 Desert Kingsnake "FATTY"
0.1 Black Rat (WV Rescue) "Roberta"