Black and Yellow Mud Dauber
I found this wasp crawling on our window at about the same time as we found last weeks Blue Mud Dauber (mid-July of 2007). This is the related Black and Yellow Mud Dauber, Sceliphron caementarium.
Like the Blue Mud Dauber, these have a very long, thin waist. I’m not sure why that is, it must give some advantage. Maybe it gives them the ability to sting a spider without getting close enough to it to risk getting bitten?
They also build nests out of mud and stock them with spiders for their young, same as the blue mud daubers do. In fact, they arguably do it better than the blue mud daubers do. The black and yellow mud daubers evidently prefer to start a fresh nest from scratch every time, like this one that we found under construction in our barbecue grill. Meanwhile, the blue mud daubers frequently take over and refurbish the nests that the black and yellows emerged from (and then abandoned).
The tendency of mud daubers to fill tubes with mud and spiders is not necessarily innocuous: they have a tendency to plug the pitot tubes that make up a critical part of the airspeed indicators in airplanes. There is at least one serious plane crash that was probably caused by mud daubers.
Aside from color, and the few differences in their habits, the black and yellow mud daubers and the blue mud daubers are basically in the same ecological niche, and I imagine that they compete directly with each other. So, most of the things I wrote about the blue mud dauber also apply here.
 Again, these wasps were big enough that the photographs were taken without the macro lens, so they don’t show as much fine detail as I might like. The surface it’s laying on is a standard playing card (the eight of hearts from a standard “Bicycle” deck) if you want a sense of scale. Anyway, the snow is finally melting, and within the next couple of weeks I should be able to start taking new pictures again instead of having to haul out all these old ones. So, hopefully the picture quality is going to improve.
 A pitot tube is a tube pointing in the direction that the plane is flying, so that air rams down its length and develops a pressure. The airspeed indicator works by comparing this pressure to the pressure in an outlet that does not have air being rammed down it, and calculates the airspeed from this pressure difference. Obviously, if the tube is plugged up by mud, it isn’t going to work right.