That thermometer dial and the hygrometer dial should be on the bottom of the terrarium because that's where your BP spends most of it's time. Right now you're measuring the temperature at the top of the terrarium which doesn't really help you because warm air rises.

I'd recommend getting a digital thermometer and hygrometer all together because those dials aren't very accurate.

You should get something like this or something similar:
http://www.walmart.com/ip/16888914?w...tRedirect=true