This is my seventh summer in my Pasadena, CA apartment, and each summer the porch light has served as a wasp hive. They return every year despite the fact that the property manager sprays when my next door neighbor complains. That seems to get rid of them for the rest of the summer, but they always come back.
They are all black, with black wings, and the biggest ones are about 3/4" (2 cm) long. In direct sunlight, they have a blue metallic sheen. They aren’t aggressive, but in the heat of the afternoon they are very active and easily disturbed.
Anyone who opens my screen door on a hot afternoon is treated to a swarm of black wasps that is rather frightening. But as far as I know, they’ve never stung anyone. And despite the fact that their hive is just inches above my front door, not one has ever ventured inside the apartment.
Now I grew up in the south, and am familiar with paper wasps and yellow jackets and mud daubers and such, and they are all aggressive enough to sting when disturbed. These black wasps aren’t, so I’m guessing they’re not carrion eaters or insectivores.
I have formed a sort of truce with them, I take care not to disturb them and they don’t bother me and they keep away unwanted visitors. They are pretty damn ugly looking, though. (But I guess they’d say the same thing about me.) And I fear that they may someday sting an unsuspecting guest or one of the neighbor’s kids.
I’ve Googled for “black wasp -flag” and didn’t find anything appropriate. The closest was the Steel Blue Cricket Hunter but I’ve watched these things fly in and out of their lair and never noticed them carrying anything. (That’s still a good link, with many fascinating photos of nests and nest removals.)