AR. This was an early swarm, I believe early March. Interesting comment. Thanks.
Jim. I do not know of any beekeepers anywhere around me. I live in a subdivision on the outskirts of town. However, I am beginning to think mine actually are from another beekeeper's hive. I was hoping they were feral.
Yes2matt. I just pulled a frame from my hive long enough to measure 10 cells in a row with a small tape measure. It was 55 millimeters, divided by 10 cells = 5.5 mm cell size. (Learned that from Michael Bush)