I have my 3 Whites Tree Frog in a nice planted exo-terra terrarium. Haven't added any plants in several months, and have been feeding my frogs crickets. This morning I saw SLUGS. Counted 4 of them. They're small, and so far my plants look OK. So do I leave them and hope Ms. Fatty Frog decides slugs will be a good snack, or do I need to get rid of them? And where the heck did they come from anyway?