Orchid bees are famous for their long tongues, which are ideally suited to sipping pollen from the narrow necks of orchids in the neotropical regions of South America, where both are common. The massive mouthparts are just one of many adaptations born out of the partnership between the orchid family and this group of bees, many of which are distinguished by their bright, metallic colorations that make them look like flying green, gold, or blue gemstones. As orchids and bees have evolved close relationships, certain species of bee have come to prefer certain species of orchid, and vice versa. The flowers even have a specialized way of transferring their pollen via bee.
“Orchids transfer pollen in sticky clumps called pollinia,” explains Jerome Rozen, curator in the Museum’s Division of Invertebrate Zoology. Different orchids have evolved shapes that place these pollinia at specific sites on an orchid bee’s body. “Some pollinia will stick to a bee’s head,” Rozen says. “Others will cling farther back on its body.”
These precise placements of pollen increase the chances that the bee will successfully fertilize another flower of the same species. A pollinia that attaches to a bee’s abdomen, for instance, is unlikely to be knocked off until that bee visits another orchid of the same kind that placed it.
Orchid bees also collect scents from flowers. Scraping up aromatic chemicals using brush-like fibers found on their legs, a male orchid bee will transfer the chemical to a pouch in its abdomen. By visiting a variety of blossoms, males create unique bouquets, which scientists think are used to impress females during mating. “It’s thought that creating a combination of smells demonstrates fitness,” says Scientific Assistant Ely Wyman.
The importance of combining scents is also suggested by the absence of females at traps—males show up in force when a single, strong scent is present, but just one aroma is not enough to draw out females of the species. Researchers use this behavior to their advantage when collecting specimens: Wyman says potent essential oils like eucalyptus and wintergreen tend to be the most effective at attracting male orchid bees, though he has also had success with less savory aromas. “I have a jar of artificial feces smell that I’ve used in the past,” says Wyman. “I don’t travel with that anymore, though. I’m too afraid it will break in my luggage.”
See orchid bee specimens on display in Life at the Limits, now on view at the Museum.