I, too, was able to fix my roach and ant problem simply by having them spray outside the house. One time my place got INFESTED with cat fleas, and at that point I had to have my whole house sprayed (my roommate didn't clean up after her kitties and the place was horrible... my poor dogs suffered for it), but to stop ants and roaches we just had them spray all around the house, concentrating on the doors and windows and bushes around the house. It worked like a charm. At the very least I would remove them from the house during the treatment, leave the room they live in untreated with the door closed and the frame lined with tape around the sides and top, with a towel at the bottom. I'd also block the vents if you have central air for a couple of days. Then I would clean their everything when I got back. I mean, let's face it... exterminators usually consider snakes a form of pests (right up there with poltergeists, hehe), so I doubt their spray is very friendly to them. They don't even let YOU back in the house for quite awhile after they're done (or mine didn't, anyway) while the fumes settle down, so I'm sure for a snake, it's not pretty at all.