Here's one from a few months ago that I never got a chance to talk about. The caught swarm (rear nuc) showed signs early on of double egg laying, and even double larvae in a single cell that you can see in the photos below. I love taking photos during inspections because sometimes you find things in the photos later that you might not have seen during the actual inspection - case and point here!
Our first thought was UH OH, laying worker, but usually laying workers deposit a dozen eggs in a single cell and they're usually not positioned in the center of the cell but stuck to the sides since a worker bee's abdomen isn't long enough to extend to the bottom of the cell like a queen's. Workers can only lay unfertlized eggs (drones) and usually only start laying once the colony has been queenless for an extended period of time. In the egg picture, you can see the cells around it have a single egg, perfecty centered, but the cell in the center of the photo has two eggs that are both attached to the bottom of the cell, fairly near the center.
After doing a little googling, I found a link to a snippet by Michael Bush (a pretty well-known and wise beekeeper)http://www.bushfarms.com/beesfallacies.htm#doubleeggs
Basically, young and inexperienced queens can be a little overzealous and sometimes lay two eggs in one cell. What we had with the swarm was a virgin queen who mated late (3-4 weeks from swarm catch to finding signs of eggs finally, due to a very rainy spring). I think this was exactly what happened in our case! This hive has since grown leaps and bounds, even giving up two frames of honey, so I think the last couple of months have proven that she's just a really committed queen who loves her job!
On to the larvae. Both eggs hatch and there are two larvae in a cell, and you can see that pretty clearly in the cell just right of center. You can't raise two bees in one cell, so one of the larvae, probably the weaker one, is removed by the nurse bees. Yes, bees cannibalize the young larvae. They'll also do this if their food supply runs short and they need the protein, or if they find larvae that are deformed, genetically inferior, or diseased. Sometimes they'll drag the carcass out of the hive, but most of the time, well, protein is protein.
And there you have it! An oddity of bee behavior that we came across this year. It's amazing how we're constantly learning new things about these little creatures!