You will find that diatomaceous earth is useless and does not work for most things that people recommend it for. It can even cause the death of your birds. What you need is permethrin powder/dust. Just look at the container and see what the ingredient is. It is sold as many things including poultry dust to put on the chickens and flea powder for your dog. Find it and powder the mound and the area around it in a circle. Would work best if you could temporarily circle the area off with some wire to keep the birds from scratching it all up. The Fire And Dust might be a stronger concentration of it but I almost doubt it. Any farm/feed store should have containers of the poultry dust. Dust your chickens completely with it. Make sure you work it all through the feathers to the skin don't just shake it on them. Also dump a bunch of it into where the birds take a dust bath. This will kill off any ants that crawl on the birds to sting them as well as get rid of/prevent any lice, mites or any other bug from attacking them. Powder any other mounds around the yard to get rid of those too. It is harmless to the chickens and other animals. Cats can be sensitive to concentrations of it though.