Mason bees, Osmia spp., are a group of native bees that are excellent pollinators. They are called Mason bees because they use clay/mud to make partitions and seal the entrance to their nest.
Within the insect world, bees are some of the greatest pollinators. One quarter of the food we eat is pollinated by the honeybee species, but there are approximately 4,000 bee species in North America. Four thousand species!
The Mason bee is a solitary bee. What is a solitary bee? Just 10% of all bee species are considered “social” bees. They form hives – with a queen, drones, workers, etc. – and include honeybee and bumblebee species. The remaining 90% of bee species – the solitary bee – nests and works alone. Every Mason bee female is a queen. Her daily life is spent seeking pollen and caring for the eggs which will emerge to become the next generation. Mason bees are a bit smaller than honey bees and are usually black with a metallic colored (blue, green, etc.) abdomen. Mason bees “nest” in holes, but “nest” is a misnomer as nursery is a more suitable term. Mason bees collect pollen and nectar and mix it to form bee bread. Bee bread is placed into a suitable hole, an egg is laid on it, then the section is sealed off with clay/mud. The Mason bee continues the process until the hole/tube is filled with egg chambers and the tube is sealed off with more clay/mud. Eggs within nursery tubes hatch within a week and emerged-larvae eat the pollen/nectar mixture (bee bread) for 4-6 weeks as they continue to grow and molt into the next instar. After the larval stage, they molt into pupae and remain in that stage for another 4-6 weeks. . Female eggs are laid further in the tube structure while males are in the outer sections of the tubes. Mason bees only live 6-8 weeks in the spring, females can fill up 4-6 tubes and lay up to 36 eggs. Solitary bees are less aggressive than social bees. When you consider that the primary job of many social bees is to protect the hive – the honey, the queen, and the eggs within – it’s easy to understand why they might get feisty when you get too close. Solitary bees, on the other hand, are too busy doing all their own work to be aggressive guardians of their nests. They rarely sting, and their sting feels much more like a mosquito bite than the searing pain of a social bee sting. Those different species of bees pollinate differently too. Honeybee and bumblebee species are considered pollen gatherers. You’ve probably seen bright yellow pollen stuck to the hind legs of these bees. Well, that’s sort of the problem. The pollen sticks to them. Some of that pollen does occasionally remain on a flower they visit, but more often than not, the pollen sticks on the bee and is taken back to the hive. Solitary bee species, on the other hand, are considered pollen spreaders. Since they don’t live in social hives, they require less pollen as a food source. Their bodies aren’t designed to hold pollen like the bodies of social bees. Most of the pollen gathered on the body of the solitary bee quickly falls off – and on to each of the subsequent flowers that bee visits. In other words, solitary bees are doing much more of the pollination work than the beloved honeybees – 30-60% more, actually. You might say they are the unsung heroes in the garden. The honeybee may get all the limelight, but the solitary bee is the one to really get the job done. To learn more about the Mason bee and other solitary bee species, as well as how to make your own Mason bee nursery, go online to Texas A&M Agrilife Extension.