Bees have a diversified natural history. thus the methods applied to study such diversity are varied. When it comes to studies of nesting biology. bees which nest in pre-existing cavities have been reasonably well studied since researchers started using trap-nests. https://www.roneverhart.com/Capsule-Hats-South-Park-Collection-Cartman-Red-Brim-59Fifty-Fitted-Hat/