Sounds like Jay hit it on the head with the ant nest. Learn something new every day. Looks like a little spraying is in order besides what the rest of the website info says.
Usually for ants, bugs, spiders, crickets, fleas, ticks, etc., I have learned and always band around the house with 5% diazinon or dursban. About a 10' band is enough. I use a hand held spreader and usually do a band fairly thick around the house and include concrete, the garage, and in and behind bushes. I do this every few weeks and especially after rains. I try to get the area where the dogs run for fleas and ticks. If spray is used then I go a couple feet up the foundation and house. Regular banding is cheaper and easier than trying to do the whole yard and keeps most things out of the house. I occasionally do the whole yard.