YES ants can harm your dragons.... I often see dead "wild" lizards outside completely covered with those lil red devils. An hour later nothing remains but the bones of the poor lil lizard.
The safest way without spraying any kind of poisions would be to get a sheet of the sticky contact paper and lay it sticky side up under your tank with a few inches sticking out on all four sides of the tank. The ants will get stuck to the paper before reaching the tank.
Good luck to you.... ants are a pain in the a$$, especially to those of us living in Florida
>>I have two B.D.'s - three month old and 4 month old. In the past couple of days, I have found a few tiny red ants in my cage. It is not a hygiene issue, as I regularly clean and discard old food. They stay in my classroom during the week. We have issues with these ants in my school and working to remedy. It is not an infestation just a nuisance. What can I do to keep them out of my tank(and from becoming an infestation in my tank) and more importantly will they harm my animals?
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Lisa 
www.beginnersbasics.com

Cricket FREE babies!