Expert: Walter Hintz - 9/4/2007

Question
Hi,  I am a historic Preservation Architect and I have an Adobe building that has a host of "bees" infesting the south wall. The adobe is located in the Anza Borrego Dessert near San Diego California. The wall has been infested for at least the last two years. Other more extant adobes in the area have the same problem. I thought when I was last out there I got a photo of one of the "bees" but they must have been to fast for me. I observed them crawling in and out of holes/tunnels in the wall. I have posted a photo of the wall/hive. My issue is that this is in a State park so insecticides may be not usable. We are trying to save the building as is and mitigate as little as possible. That means that replastering the wall with fresh mud to fill in the holes is also not a good option. I have posted a photo of the mud at http://isarchitecture.com/bees.html Perhaps you can see a bee in the photo, it looks like the hay in the mud to me.

Answer
I have looked at the photos and cannot see any adult bees.
There is a Genus of bees called Megachile that is known to nest in mud walls.  These bees are not agressive.  Perhaps you can clooect one and take it to one of th California colleges near San Diego.  Keep me informed as to what happens.