Exploiting a recently introduced species of orchid bee to clean gunk from queen excluders.

Gummed up queen excluders from honey bee hives are a significant annoyance. Online blogs and forums list several ways to clean propolis and wax from queen excluders including heat gun, hot water, solar wax melter, hot pressure-wash, various solvents, special scraper tool, hive tool followed by stiff bristle brush, freeze the excluder and then flex or bang it and, believe it or not, releasing a team of bantam chickens. Most are time consuming and messy.

Several years ago, my partner and I noticed iridescent green bees, slightly smaller than a honey bee, that curiously hovered in a perfectly stationary mode about eye level, only to zip away for a second or two to drive away an interloper, and then to return to exactly the same spot in mid-air.

We did some research and learned they are Green Orchid Bees (Euglossa dilemma), a recent introduction from Central America. They were first collected in Broward County, FL, about 160 miles to the south of our location in 2003 by USDA specialists working on fruit fly monitoring. The bees are thought to have arrived from Mexico, perhaps concealed on a wooden pallet.

Males have enlarged, hollow hind tibias, each with a hole and spongy material inside. The males visit orchids in their native environs or alternative sources of fragrances in Florida such as basil or resins oozing from rotten wood. Volatile essences are stored in the hollow leg chambers and are then thought to be "spray ventilated" to attract females. In contrast, females have typical corbiculae (pollen baskets) on their hind legs for collecting pollen and plant resins. They build their nests with propolis.

When we read that last fact, we began to wonder. We scraped some propolis from a hive during an inspection and put a sticky blob on a flat surface near an orchid bee's "territory", i.e. where one had been seen hovering. Sure enough, within minutes, a female Green Orchid Bee had alighted and began packing propolis into her pollen baskets.

The next step was obvious -- place a bunch of those gummed up queen excluders outside and hope for the best. We set several excluders outside in December after the last honey extraction, and female Green Orchid Bees did a wonderful job during the winter months in slowly but surely reducing the propolis load significantly. Perhaps they didn't do as good a job as some of the mechanical and chemical methods outlined above, but the slits are open again and we rather like the notion that it's a win:win for us and the bees.