His name is supposedly Irwin Schwab, but it must be noted that he suffers from mental problems that prevent him from truly understanding reality around him, so even his true identity might be no more than a delusion on his part. His origin is disputed, although the most commonly accepted origin is that Brum-El (a historical allusion to Beau Brummel, as well as a reference to Superman's father Jor-El) of the planet Schwab sent his clothes from his supposedly doomed planet, hoping that his wardrobe would survive, only to have it intercepted by a giant radioactive space spider. In the resulting crash, only two articles of clothing survived: the Ambush Bug suit, which was subsequently found by Irwin Schwab, and Argh!Yle!, an argyle sock with a Dr. Doom-like complex, complete with metal mask.Here's a list of every Ambush Bug appearance, the Ambush Bug Archive (gotta love the interweb); here's the wiki of the Bug's brilliant creator, Keith Giffen; and here's the essay "There will always be an Ambush Bug" on PrettyFakes.com.
Ambush Bug first appeared in several Superman-related comic books in the early 1980s. At first, Ambush Bug was a villain, named after a type of insect, and dressed in a green, skintight suit (with two orange antennae) that covered his whole body. Inside his hollow antennae, he carried miniature robot bugs that possessed the ability to teleport him around. After attacking Superman and other heroes (and being little more than an annoyance to them) Ambush Bug decided instead to be a superhero as well. He also fancied himself Superman's friend, which only annoyed the hero even more. The costume apparently then became permanently affixed to his body, and he gained the power to teleport by himself. (Again, it's unknown if this is true or just another delusion of his, as he is seen removing the costume at the end of his second mini-series.)
Lastly (but not leastly) here's Ambush Bug: The Movie.