There are a lot of things that thrive in a rainy-season country: interesting fruits, vegetables, trees, rats, mice, frogs and all sorts of insects.
Houses here are built of cement block covered in cemented-on tile for the most part. Windows are always barred, but front doors are often open except at night as there's no central air. With most kitchens outside, that usually keeps the rats outside too. Usually. Any little crack and they can squeeze their way inside. Because they are smaller, mice can squeeze in under normal metal doorways. Since upstairs Windows can be more of a downward, open vent, terra cotta tile hole, things can climb in that way as well.
One corner of one of the screens came loose in our kitchen...
Ben has suggested getting a cat to help with the mice, and who knows, that might be the best choice after the baby is born.
Spiders, flies and mosquitos are everywhere and also hard to keep out. Thankfully, most of the diseases passed by mosquitos are caught outside of the city in the countryside when people go home on breaks, so we're avoiding that kind of travel until after the baby is born.
In a water pipe hole in our kitchen lives a medium-sized frog. Every night he comes out, but dashes back in if you get too close. Ezra always says "bye bye frog" when we close up the kitchen at night. (To make sure nothing goes from there into the rest of the house.)
We always make sure all food is stored in air-tight plastic-lock containers, in the fridge or freezer. It's also important to sweep and do dishes religiously to keep pest invasion to a minimum. With toddlers and big people that aren't me who like to snack in lots of places, that gets challenging.
In addition to rodents, there are many lizards running around on the walls and ceilings here. They're fairly easy to ignore, at least.
Thankfully, we haven't had issues with snakes, though I've heard of a few issues in the city.
All of these things we call "pests" have been turned into delicacies by Cambodians. You can get snake on a stick, fried rat, dried frogs, and insects in different ways in the market. While I find that disgusting, I admire their ability to persevere and make money out of something most people would just try to kill.