As with all snakes seen near water in the Harris County area, the harmless Diamondback Water Snake is often incorrectly referred to as a "water moccasin." This is because of its generally dark coloration and its irritable disposition. When threatened, Diamondback Water Snakes will behave like all other local harmless water snakes of the genus Nerodia. As you can see from the picture above, they will usually coil up and flatten out their head, making it look arrowhead shaped. However, head shape cannot be used to tell venomous snakes from harmless ones. They will also vibrate their tail, let out large amounts of foul smelling musk which smells like a skunk, and strike out repeatedly at whatever is threatening them. This defensive behavior often causes them to be mistaken for the venomous Western Cottonmouth. Since they are not venomous, though, treatment for the bite of a water snake usually involves no more than soap and water and a bandaid.

Diamondback Water Snakes are also the largest of the water snakes found in the Harris County area, and I have personally documented many specimens over four feet in length. In fact, the state record for this species is just over five feet long. As with all water snakes, though, you will not see the wide, dark "raccoon mask" facial stripe seen on the cottonmouth. This stripe can also be seen from a good distance, making identification less likely to cause the snake to feel threatened.

Diamondback Water Snakes are occasionally found in yards when they attempt to find new water sources, especially if the yard is watered on a regular basis. Regular watering also attracts frogs and toads, which are a favored food item for these snakes (along with fish). With these points in mind, you may want to consider watering the yard slightly less frequently if you do not want to attract these kinds of wildlife into your yard.