Mason bees

Make room for mason bees

My first shipment of orchard mason bees arrived in shiny little tubes that look like drinking straws, packed in a box that weighs next to nothing. So why am I messing with mason bees in the midst of a million honey bees?

The answer is partly because they’re native—I encourage native species whenever I can—and partly because they’re fun. Then, too, I have pear trees; honey bees like pear nectar as much as Bush-the-elder likes broccoli. Honey bees are amazingly polylectic, which means they collect nectar from a wide variety of plants. They have their favorites, however, and pear isn’t one of them. Pear nectar is generally lower in sugars than other orchard nectars so, unless pickings are slim, they will pretty much ignore it.

There are several species of mason bees, but the ones native to the coastal Pacific Northwest are Osmia lignaria. They are in the same order (Hymenoptera) as honey bees, but in a different family (Megachilidae). Compared to honey bees, mason bees are extremely efficient pollinators. Just two or three mason bees can pollinate the equivalent of a mature apple tree in one season.

Like most of the native bees, mason bees are solitary. After the female is fertilized in spring, she raises the next generation by herself. She searches out comfortable digs—usually a hole or a hollow reed—and collects a pile of provisions (nectar and pollen) which she deposits at the far end. On top of this she lays an egg and then walls off the compartment with mud—hence the name “mason” bee. She continues this process until the hole is filled and then begins another.

The eggs she lays go through complete metamorphosis like a honey bee except, instead of being fed by a solicitous hoard of nurses, the developing larva has only her personal supply of grub. I say “her” although the last egg to be laid—the one nearest the opening—is a “him.” Like a LIFO system of inventory (last in, first out) the male bee is the first to hatch. Biologists call this phenomenon “protandry.” Protandry assures that the males will be fully mature and ready for the females when they emerge. (I know what you’re thinking but, no, they are not incestuous. Other brood from other females is hatching at the same time.) Protandry occurs in many species. In salmon, for example, the males arrive at the spawning grounds first, then rest (have a beer) and wait for the females to arrive. The system works.

Orchard mason bees have lots of people-friendly attributes. Since they have no large stores of honey or masses of brood to protect, they are relatively docile. They will sting if stepped on or grabbed, but they don’t fly into large hairy mammals to resolve territory issues. Unlike carpenter bees, masons use existing holes and never employ awls or augers on your siding or lawn furniture. Also, since they don’t live in large colonies, they don’t swarm onto your neighbor’s swing set or leave fecal trails on their BMWs. Furthermore, unlike honey bees, they don’t stray very far from home—put them in your orchard and they’ll probably stay there.

Lastly, mason bee houses are much cuter and smaller (and did I mention lighter?) than honey bee houses. Why not give them a try?