Technical Abstract: Chalkbrood is a fungal disease of bee larvae caused by Ascosphaera aggregata. It causes significant mortality in the alfalfa leafcutting bee (Megachile rotundata), a bee that is used extensively for alfalfa seed pollination in the U.S. Using laboratory bioassays, we previously demonstrated that fungicides can reduce chalkbrood levels in this bee. However, a control method employing the use of fungicides must not be harmful to adult bees. The toxicity of four fungicides, Benlate®, Captan®, Orbit™, and Rovral® to adult bees was evaluated using three different bioassays. In the first test, fungicides were applied to the bee’s thorax. In the second test, mimicking foliage residue, a piece of filter paper soaked in fungicide was placed on the bottom of a container of bees. The third test evaluated oral toxicity by incorporating fungicides into a sugar-water solution that was fed to the bees. The filter paper test did not discriminate among the fungicides well, and the oral test resulted in the greatest mortality. Toxicity to males was greater than to females. The use of fungicides for chalkbrood control is a logical choice, but caution should be used in how they are applied in the presence of bees.