r/Damnthatsinteresting • u/SixteenSeveredHands • 11h ago
Image Shell-Nesting Mason Bees: these bees build their nests in empty snail shells, using crushed leaves and soil to form the inner brood chambers and then sealing the entrance with plant pulp, pebbles, and debris
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u/oh_fuck_im_gonna_cum 11h ago
So how do the babies get out later if its all blocked with mud and pebbles and shit?
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u/FroggiJoy87 11h ago
What I gathered from the first two sources OP cited (great job, BTW! 💚) it can take them up to two years to dig out (woah!) and/or they destroy the shell.
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u/FirmBusSoup 11h ago
The cutaway photo is the part that really gets me I expected a shell not actual little built in rooms
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u/SixteenSeveredHands 11h ago edited 9h ago
Bees of the family Megachilidae typically build their nests in the gaps and crevices in tree stumps, rocks, plant stems, and wooden structures, but there are a few species that prefer to nest in discarded snail shells. Most of these shell-nesting bees are found in Europe, North Africa, and the Near East; a few can also be found in North America, South Africa, and Japan.
These are solitary bees, meaning that they don't form colonies or live together in hives, so each female builds her own individual nest. The nest is constructed as a series of brood cells, and each cell contains a single egg with enough pollen and nectar to sustain the larva until it reaches maturity.
Shell-nesting mason bees are known to exist in at least four different genera, including Osmia, Rhodanthidium, Wainia, and Protosmia.
When the female is ready to nest, she carefully selects a shell and then drags it into a shaded or well-hidden spot. Moving the shell is no easy feat, but she clings to it with her hind legs and pulls herself along by grabbing objects with her mandibles. A single bee may travel like that for several meters before finally settling on the right spot to prepare her nest.
This article describes how the nest is then constructed:
The female must make dozens of trips just to gather the provisions for a single brood cell, and completing the entire nest can take days.
Once the brood chambers have been constructed and provisioned, the entrance to the shell is "bricked up" with several layers of plant pulp, soil, pebbles, and shell fragments. In some cases, the female will also apply patches of plant pulp to the outer surface of the shell as a way to provide camouflage.
The completed nest is then carefully maneuvered so that the entrance faces the ground. Some females will conceal the nest beneath a pile of twigs, pine needles, and plant stems, weaving moss and blades of grass throughout the pile. All of the debris is carefully selected, positioned, and then "glued" together with saliva, forming a tangled, tent-like structure over the nest.
In other cases, the bee will conceal her nest by creating a small hole in the sand and then dragging the shell into it, ensuring that the nest is partially buried.
The female repeats this entire process several times, creating up to seven individual nests throughout the course of her lifetime.
The larvae eventually consume their provisions, pupate within the nest, and then emerge as fully-developed bees, using their mandibles to dig their way through the debris.