James and Jon,
These are likely explanations and I want to thank you for your suggestions.
However, I question these explanations.
1. The bee had an abnormally small abdomen. It was about half the length of the others' abdomens.
2. It's color and appearance were the same as the other bees in my OH.
3. If she were a robber bee, how would she have gained entrance being weaker due in part to her physical abnormaility and secondly, would a bee with this abnormality/weakness be sent out to rob as a field bee?
4. This was not the only incidence of finding a bee with this short abdomen. I found a second a day or two later on the ground outside the entrance.
5. Could it simply be that she was ousted due to the abnormality/inability to perform duties?
My hive is the one from Dadant with one deep and one shallow. They have been in there for almost two months and still have not extruded out the shallow. The swarm was small enough to fit into a quart jar, but have rapidly grown. There are probably about twice that number now. They have begun extruding a small portion of the foundation in the shallow on one side only right above the area where they have connected the two frames with burr comb and nectar. I suppose that the nectar flow has slowed and hence a slow in wax building?