East Texas.
A pit viper is a type of venomous snake. Copperheads, cottonmouths and rattlesnakes are called pit-vipers because they have a pit near each nostril which is highly sensitive to heat. This pit helps the snake in locating warm-blooded prey. Western Diamondback lives in North, Central, South and West Texas. Nine kinds of rattlesnakes are found in Texas, including the massasauga. Rattlesnakes usually rattle before striking, but if they are totally surprised, they may strike before rattling. The Western Massasauga lives in prairies from the Gulf Coast up to the Panhandle. The Timber Rattlesnake lives in East Texas. Western Diamondback lives in North, Central, South and West Texas. Nine kinds of rattlesnakes are found in Texas, including the massasauga. Rattlesnakes usually rattle before striking, but if they are totally surprised, they may strike before rattling. Most of the rattlesnakes are active at night, when they hunt for prey such as mice, rats and rabbit Facts on Texas Rattlesnakes. The most common and venomous rattlesnake in Texas is the western diamondback. Jupiterimages/Photos.com/Getty Images. Texans pride themselves on their big state, even taking pride in their big rattlesnakes. Only Arizona has more of these venomous critters. Second in size and number in Texas is the timber rattlesnake (Crotalus horridus). You don't need to know much Latin to figure out the species name. Their bodies are yellow, gray or a greenish hue with rust coloring along their backs, with a black rattle and an average length of 3 feet. Rattlesnakes are a group of venomous snakes of the genera Crotalus and Sistrurus of the subfamily Crotalinae (pit vipers). The 36 known species of rattlesnakes have between 65 and 70 subspecies, all native to the Americas, ranging from southern Alberta and southern British Columbia in Canada to Central Argentina. Rattlesnake bites are the leading cause of snakebite injuries in North America. However, rattlesnakes rarely bite unless provoked or threatened; if treated promptly, the bites are rarely fatal. The desert massasauga (S. c. edwardsii) is a Northwest and South Texas massasauga. Sistrurus rattlesnakes such as the massasaugas and pygmy are thought to be less highly evolved than Crotalus rattlers due to their small rattle and the large cephalic plates they share with their moccasin-like ancestor. Alan Tennant, RATTLESNAKES, Handbook of Texas Online (http://www.tshaonline.org/handbook/online/articles/tdr01), accessed October 11, 2015. Uploaded on June 15, 2010. Western Diamondback Rattlesnakes. Although there are quite a few species of rattlesnake in Texas, the western diamondback (Crotalus atrox) accounts for the overwhelming majority of serious venom poisonings, according to the Texas State Historical Association. Second in size and number in Texas is the timber rattlesnake (Crotalus horridus). You don't need to know much Latin to figure out the species name. Their bodies are yellow, gray or a greenish hue with rust coloring along their backs, with a black rattle and an average length of 3 feet. RATTLESNAKES. Texas has some ten rattlesnake species and subspecies, more than any other state except Arizona. Only three species interact significantly with human beings, however-the western diamondback (Crotalus atrox), the prairie (C. viridus viridus), and the eastern timber or canebrake (C. horridus atricaudatus). Alan Tennant, RATTLESNAKES, Handbook of Texas Online (http://www.tshaonline.org/handbook/online/articles/tdr01), accessed October 11, 2015. Uploaded on June 15, 2010. The banded rock rattlesnake (C. l. klauberi), named for a noted authority on rattlesnakes, Lawrence M. Klauber, is a distinctly black-crossbanded subspecies found primarily in the two westernmost counties of Texas, but it has been reported in Val Verde County as well. Alan Tennant, RATTLESNAKES, Handbook of Texas Online (http://www.tshaonline.org/handbook/online/articles/tdr01), accessed October 11, 2015. Uploaded on June 15, 2010. Also see our Venomous Snakes of Southeast Texas poster. *Note: Although there are only 4 species of venomous snakes in Texas, there are several subspecies of these snakes (11 rattlesnakes, 1 cottonmouth, 3 copperheads, 1 coral snake). The Southeast Texas poster displays the subspecies found in that area. 
http://tpwd.texas.gov/kids/wild_things/wildlife/snakes.phtml http://tpwd.texas.gov/kids/wild_things/wildlife/snakes.phtml http://animals.mom.me/texas-rattlesnakes-4403.html https://en.wikipedia.org/wiki/Rattle_snake https://tshaonline.org/handbook/online/articles/tdr01 http://animals.mom.me/texas-rattlesnakes-4403.html https://tshaonline.org/handbook/online/articles/tdr01 https://tshaonline.org/handbook/online/articles/tdr01 http://www.texassnakes.net/pictures.html
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