The hapless males transfer larvae to females when mating. All the male bees the scientists examined carried larvae. The female bee makes a nest hole in the ground, provisions it with pollen and lays her eggs there. If she's carrying the parasitic larvae, they drop off into that carefully built home with its well-stocked larder. All the work of the poor bee mom ends up producing more parasitic beetles, rather than more bees.
Cautious bees are likely to lose prospective mates to other males.
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