The Radscorpion is one of the many mutated enemies you encounter across the Capital Wasteland. Unlike other adversary's, the radscorpion doesn't seem to have a weak point and takes the same damage everywhere but the legs.
There is a larger stronger species called Giant Radscorpions. They can be a hassle to kill at a low level. If you've downloaded Broken Steel, a new variant of radscorpion appears, the Albino Radscorpion. These are much stronger.
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