Yes, you need a thermostat to control the UTH. (The UTH just plugs into the thermostat.) It will have a probe on a cable that you place directly over the heat mat. This will keep the UTH from getting too hot and injuring your snake.

In addition the Acu-Rite indoor/outdoor thermometer hygrometer works very well. I place the unit on the cool side and run the small probe to the same location as the thermostat probe. Be sure and scrape the little sticky pad off of the temperature probe. This will prevent the snake getting stuck to any adhesive (a related word of caution - never use tape or anything with adhesive inside the tank).

To prevent the snake from bumping the thermostat and thermometer probe away from the UTH I secure it in place with clear silicone sealant. It's the same thing that's in the corners of your tank so is harmless when dry.

Thermometer/Hygrometer http://www.walmart.com/ip/Acu-Rite-I...mometer/896347

My choice of thermostat http://lllreptile.com/store/catalog/...re-controller/

The best type of thermostats are called "proportional". They adjust the power going to the heat device according to need, not just on/off like the more economical one in the link. The proportional one's are, however, significantly more expensive.