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There is now a paper wasp nest hanging from the eaves of my bedroom. Not very big, I supposed about a hundred chambers and about 7 to 10 adults in total. I observe it every now and then.
It just occurred to me that when the larvae first hatch, they are so small compared to the chamber diameter. So here are two questions:
Social wasp larvae hatch from an overhanging egg, and they grow up through a series of skin moults, typically 5 in number. The shed skins accumulate terminally behind their pointed anus, where the egg chorion peduncule remain. These wasps have a special body construction and skin texture (e.g. abdominal lobes, numerous spikes) that allows for pressing against the cell walls.
You can see these traits from high-resolution images shown in the larval descriptions: Florida Entomologist, 95(4):890-899 (2012) https://doi.org/10.1653/024.095.0411 Sociobiology 63(3): 998-1004 (2016) http://dx.doi.org/10.13102/sociobiology.v63i3.988
Finally, it should be minded that gravity doesn't affect small insects in the same way it affect larger mammals like humans. This means it way takes less effort and sticky secretions for these bugs to hang onto walls than we typically imagine by common sense.
I don't know of any dedicated estimations on fallen larvae, but I guess the event isn't common, unless perhaps in abnormally structurally-challenged nests.
What I can say from observing an abandoned nest, larvae have a connection to the chamber ceiling. I don't know what it is, exactly, but looks like some form of glue.
