What a wonderful season for a walk in the woods. Wildflowers like trout lily, blood root, and spring beauties abound on the forest floor. While photographing some spring beauties, I was lucky to spy a small bee loaded with pollen. This bee was pretty in pink after spending the day collecting lavender pollen from spring beauties. The dense hairs on the legs of this bee are called scopa and they bulged with pollen. Spring is the season that many of our native pollinators are busy at work. Why do so many insects gather pollen? A remarkable deal was struck between insects and flowering plants more than 65 million years ago. Plants agreed to provide insects with food in the form of nectar and pollen and insects agreed to reliably carry pollen from one plant to another to complete the task of sexual reproduction. Along with beetles, flies, and butterflies, bees are among the premier pollinators on the planet.
Plasterer bees and yellow-faced bees, known as colletid bees, are relatives of honeybees and bumblebees but, unlike their cousins, these bees are solitary. Rather than living in a communal nest, each female plasterer bee constructs a subterranean gallery of her own to serve as a home for her brood. The interior surface of the burrow is lined with a thin, glossy, translucent material produced by the bee. The habit of coating their galleries gives this bee the common name “plasterer bee”. Yellow-faced bees nest in hollow stems of plants, tiny crevices in the earth, and old burrows constructed by other insects. Burrows are provisioned with “bee-bread”, a concoction of nectar and pollen from flowering plants that bloom early in the spring. This yummy delight is food for the larvae of the bee that develop within the galleries.
Female colletid bees lay eggs in the well stocked brood chambers and the eggs hatch into larvae that develop during the growing season. Plasterer bees and yellow-faced bees are important pollinators of several native plants. Although they are not considered social insects, they are often abundant in sandy soils with thin vegetation. While exploring a golf course on a rather blustery day, I was delighted to see dozens of small plasterer bees zooming inches above the ground. While swarming bees at the margin of play might dismay some golfers, there really was no cause for worry. Unlike yellow jackets, bald-faced hornets, and other stinging terrors, plasterer bees are docile and harmless. Over large areas of this balding zone, several burrows could be found in each square meter of ground. The plasterer bees were not responsible for the balding turf. They simply colonized areas where the ground cover was naturally thin. If you should see swarms of small hairy or metallic bees constructing or emerging from galleries in soil of your garden, resist the urge to treat them with insecticides. Several families of native pollinators such as digger bees, andrenid bees, halictid bees, and our friends plasterer and yellow-faced bees nest in the ground. Enjoy these spring beauties and give them a break. They pollinate plants and keep our planet humming.
The “Pollination Conservation Handbook” by Shepard, Buchmann, Vaughan, and Black is a wonderful resource and served as a reference for this Bug of the Week.