Osmia lignaria

Osmia lignaria, the blue orchard bee, is a mason bee native to North America and is active early in the spring season. It nests in pre-existing cavities, which is why growers can support it with bee hotels and managed nesting blocks. It is especially valued for pollinating early-blooming fruit trees such as apples and pears.

Blue orchard bees are solitary cavity nesters rather than social colony builders like honey bees. Because they are active in cooler early-season conditions, they can be effective when some crops bloom before honey bee colonies reach peak activity. Many orchard managers use them as a complementary pollinator, not a complete replacement.

The species is commonly known as the blue orchard bee because females can show a bluish sheen on body hairs and a metallic appearance. You may also notice solitary nesting behavior in drilled wood holes or reed stems. These bees have robust foraging during cool spring windows.

Its peak activity is typically in spring, aligned with early blooming fruit trees in temperate regions. Because of this timing, it is often introduced in managed orchard programs for early flower set. The species therefore has practical value in low-temperature pollination periods when other pollinators are less active.