Jeri (and FML),
 
You might try the herb rue.  I have been planting rue in my gardens for
years to keep ants away, and the dried herb works well too.  You can obtain
it from wiccan or new age stores, apothecaries, herbalists, and online at
www.azuregreen.com (look for herbs).  I've never used it near domesticated
animals, and am not aware of any contra-indications or toxicities (although
large doses can be abortifacient in humans, so I wouldn't use it near
pregnant jills), but if someone has any further knowlege on this, please
let me know.  Barring that, sprinkling it round the cage couldn't hurt.
Also, follow the ants and try to ascertain where they gain entry, and
sprinkle the rue there, as well as on doorsills and anywhere you might
think they could get in.
 
Just my $0.02,
Rhyakat
[Posted in FML issue 3357]