While working in my beeyard yesterday I sensed a change in the "tone" of the yard. I walked over to my Top Bar Hive and realized that there were these huge black bees barging in and out of my hive. I couldn't really tell if my Carniolans were doing battle, but there were seriously not happy, was my impression by the "tone". I ran to my computer and felt that they were robbers. I made the entrances very small, as best as I could, and began swatting away the interlopers, my girls seemed to be happy with what I was doing. Eventually the tone returned to normal and I could see there were no more of the black bees around. What the heck was this? I am in the beginning of my second year, I have one top bar and 4 Langs. What I am reading says it is too early for robbing. Who are these black bees, they were at least twice the size of my girls.