Van, I'm not sure. They seem to be pulling larvae in small qty's each day - of all ages. It's the only hive doing it. I've never seen this in person before. Our temps here have been 55-70 days, and 37-50 nights. The hive has about 6 medium frames of bees right now, which is to say, the lower box is completely full of bees, and the upper box (1 of my last remaining deeps) has part of a frame. Last check 2 weeks ago showed 3 frames of brood, and the new queen. The deep frames above are 70% full of capped honey. If things go right, this hive should "explode" in size in the next 3 weeks. So ... I'd love some advice on this one.
Alan, you ask for advice regarding the larva on the entrance; I counted maybe 12 larva which is a very small percentage for 3 frames of brood. Maybe normal as most larva are dragged off never seen by the beekeeper whereas your robbing screen just happens to catch the larva for viewing. With some of your nights in the thirties F, maybe chill of perimeter larva of the brood nest that chilled. Larva needs to be 90-92F and at what temp the larva chill and die is not known by me.
As long as I see PEARL WHITE LARVA in the brood nest, 99% of my worries vanish. The pearl white larva is something I always look for in the hive. Kinda of an: all is clear sort sort of issue with pearl white. I am not forgetting mites, beetles, stores; just sticking to the subject of larva.
Health to your bees.
