Its snake season so it is important to be able to tell the difference between poisonous and non poisonous snakes. In Northern Virginia there are only two types of poisonous snake and they are the Copperhead and Timber Rattlesnake; a lot of people will say Water Moccasins but they do not range this far north. The following link was put out by the University of North Carolina, some of the species of poisonous snakes are not relevant but the information on telling the difference between poisonous and non poisonous should be very useful.