You would not believe the amount of spiders that live in my mints. They like it when the mint gets tall and bottom leaves fall off inside.
The rats don't seem to like catnip. They will go way around the big patches to get near the chicken food. I've allowed the plants that have come up alone the fence to stay and spread. It covers over half of the 35x16 large fowl run fence now. The chickens won't eat it but do like hanging out under the shade it casts.
I can't say anything about catnip and mosquitoes. I don't ever see many mosquitoes here even with 60 acres worth of pond with half a mile or next to us.
Because there are trees and marsh that dries up for summer, there is habitat for tons of little birds that eat the things. The ponds are stream fed and there are fish. So can sit outside pretty safely here.
I've been eradicating mint from my garden, and letting that and lemon balm pop up at will around the perimeter of my yard. I just dumped a w/b full of mint rhizomes under the mail box where poison ivy has taken over. If the mint does not drive out the PI, the next plan will be to put heavy cardboard down, or some scrap lumber.
I have peppermint on both sides of the back door and spearmint by the wellhouse. Makes for a nice fragrance when brushing by it.
My cats are immune to catnip now. Too much growing that they brush against. They actually don't seem to like the scent anymore when I crush leaves and offer it. I'm thinking of ordering some valerian root for them, even though I hate the smell of it.