An incubator that draws excess heat from a honey bee hive warms up managed Osmia lignaria bees so they can pollinate early-blooming fruit trees like cherries, apples, and almonds. A new study shows the hivetop incubators are effective, with little effect on the honey bee hive temps below. Shown here is a hivetop incubator atop a honey bee hive, with a small exit hole from which O. lignaria bees can be seen emerging.