The coloration and the bands can be somewhat variable throughout the native range. The snakes are about 18 inches long after hatching. Adults are generally 4 -5 feet long and as big around as an adult humans' thumb. On Guam snakes in excess of 9 feet have been captured. Juveniles, up to about 3 feet in length eat lizards exclusively.
Adults switch over to warm blooded prey, rats, mice, shrews, birds and bird eggs.
The fangs have a groove and the venom runs through the groove into the wound. It is a mild venom roughly equivalent to a bee sting in an adult human, although babies that have been bitten have had to be hospitalized. There have been no deaths from a Brown Tree Snake bite. How well the venom subdues a prey animal or if it is more of a digestive aid is not really known. Larger snakes will use constriction to subdue larger prey.