We have a huge problem with ants. Usually it's during the warmer months and outside. This past year, they invaded our tortoise pen in a really bad way. Our biggest tortoise, Max, was running (as best as torts can do) around frantic for days before I figured out the problem.
Since you can't spray pesticides around animals, I needed to try the method my tortoise care email group (what?) recommends for homemade ant bait. This doesn't kill the ants on contact, it allows the workers to take the bait/poison back to their nest so it will kill the queen and thus the nest.
Supplies: boric acid, sugar, water, cotton balls, glass jar with lid, and a plastic container with a lid.
For a 1% solution, mix the following:
1 tsp boric acid (if you find the ants dying right away, lessen this to 1/2 - 3/4 tsp)
6 tbsp sugar
2 C water
Mix together in a glass jar until dissolved. Label and store safely and somewhere way out of reach.
Take your plastic container and make holes around the bottom - big enough for the ants to get in. Soak a few cottons balls with the mixture (be VERY careful when handling this!) and place in the container, then put on the lid.
Place the container near ant trails. With the small openings and lid, our tortoises could not get to the poison so I was able to put this in their pen. If you are using this around larger creatures, secure the container with something heavy on top. Freshen 1-2 times a week depending on the success of it or the evaporation of the mixture. You can also use the decreased strength on a regular basis to keep the ants away.
Fast forward to NOW, when we are supposed to be ant-free since it's winter...only it's very warm out. So what do I find in our downstairs bathroom? Ants yet again. My first reaction was to spray pesticide. But all that does is make a big smelly mess and kill the ones inside, while they keep coming and coming from outside. And this time, we couldn't tell where they were getting into the house.
I decided to try my boric acid mixture and put the container into the shower. I gave strict instructions to Greg NOT TO SPRAY the ants (because I knew he would). We want them to carry the poison back to their queen to kill the whole nest! And sure enough, within a few hours a huge long line of ants were filing into the shower and surrounding the container. This also let us discover how they were getting in. It's been a couple of days and I just took the picture above - hardly any ants around. Now Greg has asked me to make up more of these to put outside where he has seen more ants. Even though we have no animals outside right now, I'll still want to keep the container anchored with a lid so no roaming cats, dogs, or lizards get to it.