you can sprinkle cinnamon, fairly thickly, around where they're coming in and along the path, and it deters them. obviously, this is good b/c there's absolutely no toxicity concern for kids or pets.
in addition, you can make a mix of:
10.5 oz water
3 oz tabasco sauce
2.5 oz Dr. Bronner's liquid peppermint soap
mix the ingredients together and then pour into a hand-pump spray bottle. spray where the ants are coming in. while you wouldn't want to ingest this, it doesn't have any toxicity concerns for you or your kid.
as an aside (of sorts), the woman who said that all of our concerns about toxicity (and anti-bacterial hand soap) are over-stated is sadly, and seriously, mistaken. there is ample scientific evidence to contradict her position. while her 7-year-old may ~seem~ "just fine," the reality is, the toxins that we use in our homes build up in our systems, and they can lead to long-term problems, including problems with endocrine glands which interferes with hormone communication throughout the body; kidney and liver damage; lung damage; paralysis; sterility; suppression of immune function; brain hemorrhages; decreased fertility and sexual function; heart problems; and the list doesn't stop there. again, there have been ample scientific studies, not just anecdotal evidence, to support this position, which directly contradicts her assertion that folks are worrying about nothing.
a 1987 study under the auspices of the National Cancer Institute found that children who lived in households where OUTDOOR pesticides were regularly used were six to nine times more likely to develop some forms of childhood leukemia; the figure increased four times when indoor pesticides were regularly used. and that's not even touching on the number of children (and pets) who are harmed our killed by accidentally ingesting pesticides; pesticides are the #2 cause of household poisonings in the US.
not only that, but when we use pesticides (and fertilizers) in our homes and gardens we don't just contaminate our own land, air and water, we contaminate that of the entire community.
Don't let other people's denial deter you from seeking safe solutions. there is absolutely no reason to use commercial, chemical pesticides when there are so many natural pest-control methods that have worked forever and are often even more effective b/c many pests are beginning to develop immunities to the chemicals (which doesn't happen w/ natural solutions b/c Mother Nature has a way of making things evolve together).
sorry to jump on my soap box, it's just that this stuff is dangerous and it bothers me when people are deliberately ignorant about what's going on.
best,
K.