I’ve seen unicycling fleas at the circus so you must be able to get a small enough Uni. You’ll need a good magnifying glass to check if you have the right number of pedals though. I wonder as ants are supposed to be very strong for their size whether they could run a Guni with better than a 1:2 ratio?
A fun thing for young kids to do is to go out in the swamps with slingshots made with rubberbands and shoot dragonflies. Then bring them home and put them on the fire ant nest next to your front door.
Behold, you have just dealt the ants their feast for the day!
I have killed (or attempted to kill) many fire ants in Florida. You can destroy one ant-mound only to see another pop up right next to it. I never tried on a unicycle.