There's little that you personally can do around the house, it really takes a professional treatment to kill them or keep them out of your house. The over the counter stuff is mostly crap. Fipronil (Termidor) is what the best pros use, but it has to be injected into the soil around your house to form a barrier. Chances are, they won't end up in your house. Termites are everywhere, especially in FL and I assume in most of TX.
Honestly, they rarely will bother anything living, so your trees are most likely OK. In the wild, they are a beneficial insect, it's just in your home that they're undesirable to put it mildly.
In the top picture, see the one with a huge brownish head? That's a soldier, its job of course is to protect the workers, mostly from ants. The small white ones are workers.
If you're really that worried, then you can get a preventive treatment. Just call around for pricing, be careful with the big guys like Terminix, they can really take you for a ride. If you can find a smaller independent operator, I always prefer working with them for stuff like this. Check Angie's List, stay away from Home Advisor!! Depending on the size of your home, you're probably looking at around $1,500 for a preventive treatment.
Or like I said, sign up on a quarterly contract with a good independent pest control company, have them inspect your home at least annually, then just treat as/if needed.