We usually have them coming in all of our windows every spring and summer. I read about this liquid ant trap product and is has worked for us. I put them on the outside of the window seal and anywhere you see them in numbers and it has done the trick. I am not sure if it is pet safe though so you may want to check that. We have an indoor cat and only use this product outside.

Amazon.com: TERRO PreFilled Liquid Ant Killer II Baits 6 Pack T300: Patio, Lawn & Garden