This is a Snakefly. They are found in Europe, Asia, and the Western United States. At one time they were considered to be closely related to lacewings, but now they are classified in their own order (Raphidioptera). They are beneficial insects to have in your garden, as both the larva and adult are predatory. They eat aphids and many other small insect pests. With that in mind, if you see one in your garden, be sure to say, "Thank you!"