On June 30th I grafted into my cups and put them in my cell builder. They started 21 queen cells from my graft. I checked on them on day four after my graft and there were still 21 cells. I opened them up today and noticed that there were now 2 cells. The remainder had been aborted. It looked like the bees cut them open and removed the queens inside, as it appeared that the caps had been cut open. I looked for a virgin to see if that could have caused it, but to no avail. There is no virgin, or any queen in this hive because the larva was grafted from 1 day old larva, and the cell builder had no larva when I grafted, just young nurse bees. What would cause them to abort all those queen cells?