Yote - use a light dusting of Sevin dust inside the box of the camera. Used carefully it won't harm a thing. It don't take a whole bunch.
I had ants in my trail cams too. Mine are protected by metal bear boxes so I used Sevin dust inside the box and that took care of my problem. If you do not have a metal protetion just the trail cam box - then - I did treat the inside of a Moultrie plastic box last yr and the dust is still there.
You can spray the inside of a plastic bag, 3 second burst is all that is needed (DO NOT SPRAY ON CAMERA) with any household insecticide - I use Raid House and Garden -place your trail cam in the bag and then seal the bag with a twist tie. This will fumigate the camera.
or you can always use Sevin dust at the base of the tree tool Sevin does not have much odor or spray the tree trunk.
All I can think of since I worked in the bug industry.
JW