Yesterday I saw a "large bee fly"... fascinating! I looked it up and they are parasitic to solitary bees, which would imply that I have those around somewhere. I "googled" them, and they look to me like honey bees. How can I tell the difference, and where do they nest?
Large bee fly: http://www.biosurvey.ou.edu/okwild/m...s/lgbeefly.jpg