Updated March 13th: The USPS says these stamps will be issued August 3rd in Richmond VA. That would coincide with the first day of APS StampShow.
From the USPS, November 22nd, 2016:
This stamp pays tribute to the beauty and importance of pollinators with stamps depicting two of our continent’s most iconic, the monarch butterfly and the western honeybee, each shown industriously pollinating a variety of plants native to North America. These particular species exemplify the ecological service provided by all pollinators, which include other insects, birds, and bats. Crop pollination by insects contributes approximately $15 billion of produce to the U. S. economy each year. Trending declines in their populations alert us that pollinators are helped by planting pollinator gardens with native flowers or heirloom varieties of fruits and vegetables. Art director Derry Noyes designed this stamp pane with existing photographs.
This subject was previous covered by the USPS in 2007: