Above and left: Developing larva inside the larger mass, which was about the size of a U.S. quarter.
Here's one reason not to stick your hand in the nest cup when monitoring your bluebird trail. You might encounter a Queen bumblebee that does not appreciate your interference.
Out of about 100 pole-mounted nestboxes on my trail in NE CT, I find 1-3 bumblebee occupants each year. They tend to be inside chickadee nests, but I found this one in a Tree Swallow nest. The Queen bee came buzzing angrily out of the box. I looked under the nesting material and found the honeypot (at the bottom) and a waxy mass (top) that contained developing larvae. At first I thought it was a dead nestling, but it was hard and waxy yellow. The honeypot had a flat "mouth" and was filled with watery nectar.
Because the nestbox is in the backyard of a family with serious bee venom allergies, I needed to remove the nest.
The Queen bumblebee makes the waxy honeypot and regurgitates nectar into it. She then drinks from the pot while brooding her eggs. Four to 16 eggs are laid in a ball of pollen, which is then covered with wax (the mass at the top of the photo). The eggs hatch in about 4 days, and become adults n 4-5 weeks. The queen often starts another batch of eggs while the first batch is in larval mode. See more information about honeybees here.
Many monitors conclude that bumblebees take over abandoned nests. I suspect they CAUSE abandonment. I have heard of at least one case (in a box monitored with a nestcam) where a bumblebee was actively going into a chickadee nest during the egg laying period. The monitor (JC) said: "When the bee flew in, it immediately burrowed. The dee waited about a minute before entering and I'm assuming located the bee by its buzzing. She plucked around in the nest, found it and grasped it with her beak 3 times. Each time she shook her head and the bee was released. The last time she kept it in her beak and flew out of the nest and landed a couple of feet away. She fought with it for about 10 seconds and it flew out of her beak and back into the nest. It was actually quite a battle." (The monitor removed the bee and the chickadee returned to the nest, and laid an egg the next day.)
You cannot begin to preserve any species of animal unless you preserve the habitat in which it dwells. Disturb or destroy that habitat and you will exterminate the species as surely as if you had shot it. So conservation means that you have to preserve forest and grassland, river and lake, even the sea itself. This is vital not only for the preservation of animal life generally, but for the future existence of man himself—a point that seems to escape many people.
-Gerald Durrell, The Nature Conservancy
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