They are generally olive green to brown, although they may be somehwhat yellow or have slight saddle-like splotches off red.Brown tree snakes may be any length from 18 inches as juveniles to over 8 feet long as adults,The saliva of a garter snake may be toxic to amphibians and other small animals. For humans, a bite is not dangerous, though it may cause slight itching, burning, and/or swelling.Juvenile brown tree snakes (Boiga irregularis) are 15 inches long, and adults may reach 10 feet in length. They are brown, olive green or yellow in color,Shiny blue-black in color. Light brown at tip of snout. Bright red to orange scales along sides. Creamy pink belly. Small, flat head. Small, black eyes. Smooth dorsal scales. Many other poisonous snakes share the abode, including coastal taipans, eastern tiger snakes, black tiger snakes, king brown snakes, red-bellied black snakes.