Gail
Your photo is of a predaceous diving beetle. You probably live near water!
These beetles are found in and around water. The adults will fly to lights at night, but usually are found swimming in water. The 'stinger' you saw was probably the rear legs held together in the back making it look like a stinger - see photo - http://bugguide.net/node/view/287223/bgpage
The larva and adults of these beetles feed on small fish, mosquito larvae, other aquatic invertebrates, and sometimes tadpoles and salamanders.
