You sure that's an ant hill...? It's in a line and 3 ft across? Or is it just a large line of mounds with ants over them?
I'm just saying... Moles and voles (as well as other burrowing mammals) will make very similar holes and mounds. They'll dig the fuck out of your yard. If you're using Raid and other products without success, you sure it's the ants and not some random mammal screwing your day?
There are also, depending on where you live, Cicada Killers - which are a monster-sized wasp that makes burrows. They leave during the day and by the time they come back the spray or whatever may have already sunken deep into the ground, or they could have found some alternative entrance.
I'm just saying... Moles and voles (as well as other burrowing mammals) will make very similar holes and mounds. They'll dig the fuck out of your yard. If you're using Raid and other products without success, you sure it's the ants and not some random mammal screwing your day?
There are also, depending on where you live, Cicada Killers - which are a monster-sized wasp that makes burrows. They leave during the day and by the time they come back the spray or whatever may have already sunken deep into the ground, or they could have found some alternative entrance.