Native of the Month: Blue Orchard Bee

by | Apr 13, 2022 | Native animals

Blue Orchard Bee – Osmia lignaria
What’s blue, beautiful, beneficial, and buzzes? The blue orchard bee. Native to the US and Canada, these little bees become active in early spring and get right to work pollinating some of our favorite plants. They are known to be excellent pollinators of apple, pear, and cherry trees as well as fruiting shrubs in the northwestern U.S. In fact, recent studies have shown that native bee species, including the blue orchard bee, are two to three times more effective pollinators than non-native honeybees! Washington State has over 600 species of native bees. Although many animals function as pollinators (such as butterflies, beetles, flies, wasps, and even birds and bats), bees are the most effective because bees, apart from honeybees, actively collect pollen to feed their young and themselves. Other pollinators only search for nectar and get pollen stuck to their bodies as a result. The second reason is that bees tend to visit flowers of the same species within a foraging trip, so cross-pollination happens much more readily.  Unlike honeybees and bumblebees, blue orchard bees are solitary and don’t live in a colony. Each female builds her own nest in existing tunnels in wood or hollow stems. After choosing a nesting hole, she places one egg on a pile of nectar and pollen and then seals it off with a thin divider of mud. She creates several more sections in this manner and usually constructs these divided nests in two to four nesting cavities.  
Eggs that turn into male and female bees are different. Female eggs are laid first at the rear of the nesting hole, and males’ eggs are at the front. Males are smaller, take less time to develop, and emerge first which allows the females to emerge when they are ready. This differentiated system also allows for better species survival because the eggs at the front are more susceptible to predation and male survival is less important than female survival (since females produce the next generation of eggs). How does the female bee control whether she lays a male or female egg? After mating, the sperm is stored in a separate compartment inside her body, and she can control whether sperm gets released to each individual egg. Fertilized eggs become females and unfertilized eggs become males.   There are several ways to attract and support blue orchard bees near you. Where possible, allow dead trees or snags to remain in the landscape. Plants with pithy stems, such as raspberries, provide excellent habitat for these small cavity-nesting bees. Although blue orchard bees are solitary, they happily live in communities with fellow bee neighbors and are often delighted to take up residence in human-made “bee hotels”. Bee hotels can be easily made, but maintenance is required to limit the spread of disease and harmful mites. Learn to build your own bee hotel!