If a flying insect has a habit of burrowing inside of mortar that functions as foundation for buildings, then there's a good chance that he's a "mortar" or "masonry" bee from the genus Osmia. Although these guys are a tad tinier than honey bees, they otherwise look a lot like them.
Spotting Mortar Bees
Mortar bees emerge in the spring and summer months each year. They have a conspicuously furred look, with rather squat physiques. Their basic coloring is a combination of yellow and pale brown. They lead independent lifestyles, unlike honey bees, and as a result usually are seen solo. It isn't rare for them to live in similar areas to each other, however, as they tend to gravitate to similarly appropriate places to nest. Mortar bees frequently come across somewhat disoriented in manner when they fly around on their quests for nesting areas.
Burrowing Inside of Mortar
Mortar bees' choices in nesting paved the way for their moniker. They often diligently carve out tunnels inside of smooth mortar. Once they do so, they insert combinations of pollen and nectar inside of the tunnels, and then promptly deposit their eggs. If the mortar is hard rather than smooth, they use openings that were there previously instead of taking it upon themselves to establish them.
Keeping Mortar Bees at Bay
If mortar bees are affecting the exterior of a building, their burrowing activities often can be dissuaded by fixing parts of mortar that are fragile and, therefore, not as sturdy as they should be. Filling in the problematic joints generally does the trick. It usually is beneficial to do this at the end of the summer, when the bees are calmer. If you notice a couple of insubstantial crevices on a building's wall, don't panic. It's unlikely that mortar bees will do major harm to the framework of establishments. Notably high numbers of mortar bees often are problematic, however. Piles of bits of mortar gathering on the ground by walls often signify the presence of these bees. Note that mortar bees don't consume mortar.
Although mortar bees can be nuisances to buildings, for the most part they're innocuous creatures. They're not fierce insects and tend to ignore human beings. While the females are capable of stinging, they refrain from doing so unless they're pinched. Stings from mortar bees are extremely rare.
- Salford City Council: Mortar Bees
- Stockport Metropolitan Borough Council: Mortar/Masonry Bees and Mining Bees
- The Society for the Protection of Ancient Buildings: Technical Q&A 17 -- Masonry Bees
- Gateshead Council: Mason Bees
- Natural History Museum: Insect Identification Sample Sheet
- Solihull Metropolitan Borough Council: Mortar Bees