Should I drill a hole (with a hole saw) into a ten gallon terrarium for ventilation?!?

[Guitars and Tarantulas]

Ok, so I have a terrarium, and I am getting ready to put an A. Avic (pink toe tarantula) into it but I need to have ventilation to prevent molds from going! It is a ten gallon tank with a screen lid and a pad lock. The tank is on its side, because pink toe tarantulas need more height than floor space, because they are arboreal (tree dwelling). With the lid on the side, one side of the tank is basically a screen, if it matters. So please tell me, should I drill a hole, or is this good!? Thank you!
I meant growing, going lol.