Is the Amdro you're using fresh? That would be the only thing that I can think of.

Keep in mind that it can take 3 to 6 weeks after the baits are distributed to see results, this is not something that produces results in a short time.

Thanks. I think they might actually be gone as of yesterday, so you might be dead on regarding the 3-6 weeks. I've just never seen it take more than a couple of days in my experience.

I have noticed the same thing with fire ants around here too.
bought a fresh container of amdro the one that has the very small bait modules that you pour out near the fire ants and the fire ants around here just seem to investigate it for hours and never carry any of it back. when a few years back the fire ants used to investigate the poison food bait modules and then after about 10 or 30 minutes carry the amdro back to the nest i am wondering if they built up a resistence to that amdro type of fire ant bait. I am in Florida by the way.

I've seen the same thing with Amdro this year. Last year they swarmed the Amdro granules within seconds...I use to refer to it as "ant crack" . This year, they just walk over it. That's happening on all the mounds - they ignore it :-(