I found these ants underneath an oak tree. Could be some kind of arboreal Camponotus sp?
Location: Katy, TX (close to Houston)
Date: Today (3/15/16)
Color: Head and thorax - chestnut color (reddish brown), gaster - black.
Size: different sizes, from 3 mm to 6 mm.
Surrounding: Close to oak tree near residential area
I didn't see the nest, it was spotted walking on my car which parked under the oak tree. Aldo, please ignore the alate on the first pic, i don't know what species it is but definitely not the same species with the ants. Thank you for the help!