Alfalfa leafcutting bees (Megachile rotundata) are solitary bees that lay eggs in narrow cavities, either natural or artificial, such as in a next box. The species is a critical pollinator of alfalfa crops. A new study led by researchers at North Dakota State University examined how the microclimates on different sides and levels of nesting boxes influence the bees’ egg-laying preferences and ensuing number of offspring. (Photo by Whitney Cranshaw, Colorado State University, Bugwood.org)