How to avoid ants getting inside iMac screen?

Sometimes during the year seasons ants becomes a hassle in my region, and quite a few of ants are walking around in my desk. Often some get inside my screen, I try to take it off but I realise it's in within the glass, so funny, but one died inside the screen and now the screen got this little dot in it, which of course cannot been seen on screenshots, however I took a picture to see that. In other occasions they just walks around as it was their natural habitat.

They may get inside from speakers, i guess, so is there something to avoid this kind of things?