Alfalfa leafcutter bees (ALBs) are important crop pollinators that nest in aboveground cavities (e.g. straws). Much of the biology of these bees can be understood by studying their nest architecture. On farms, these bees are exposed to pesticides which can impair their ability to build nests and reproduce. We will examine how exposure to prevalent insecticides, neonicotinoids, affects ALB nesting behaviors by studying nest structure and size under different insecticide treatments.