Which is a good thing, because he's a stinkbug. Specifically, a green stinkbug. As you might've guessed just by looking at him.
Stinkbugs don't like to be disturbed. In fact, when they are, they make a stink about it. A real stink. The odor is described as the essence of skunk with notes of dirty sock and a hint of cilantro. It oozes from glands when they're upset; if squashed, they get the last laugh by releasing lots of their repugnant pong.
Birds aren't fond of the fluid's taste, which is presumably as bad as its smell, so the stinkbug's perfume makes a great defense. A predator that catches it may drop it in disgust, giving the stinkbug a chance to escape. Still, many birds, spiders, and other insects aren't repelled enough by the smell or taste to forgo making a meal of the stinkbug. Maybe a stinkbug is akin to Limburger cheese or truffles in the animal world.
(Some stinkbugs will even eat other stinkbugs. Then they're put on trial and the judge gets to say, "Odor in the court!")
This stinkbug is probably looking for a place to overwinter in the garden, someplace slightly damp and protected from the elements. Next spring he (or she, I guess) will emerge to lay eggs.
My Audubon field guide makes it clear that green stinkbugs aren't exactly beloved: "This pest damages apple, cherry, orange, and peach trees, and eggplant, tomato, bean, pea, cotton, corn, and soybean crops." It probably leaves the top off the toothpaste tube and dishes in the sink, as well.
Just for fun, I decided to find out how you say "stinkbug" in German (since so many words are much funnier in German than in English, at least what I remember from my many years of German back in the day). Not knowing where my German-English dictionary is (and feeling about as lazy as a late-fall stinkbug on a daylily leaf), I decided to use an online dictionary.
This resource didn't have an entry for "stinkbug," however, and instead asked me if I'd meant to look for "shooting box steamships." Well, yeah, of course. Isn't that obvious?
