Continuing our exploration of the buzzing insects devoured by the bee-eaters, today I am happy to share with you the story of how I discovered Leafcutter Bees (Megachile sp.). Several years ago I was pruning the Sodom Apple tree in my garden, cutting away the dry dead stems, when, in one of the branches that I removed, I noticed this:
I was fascinated by these bits of bougainvillea tucked so neatly into the branch. We found two more empty stems sealed this way and left those on the tree. But my curiosity got the better of me and I broke this branch to see what was inside.
Beautiful pink packages all lined up! Figuring these were nests of some sort, I felt bad about the disturbance I had caused. I tucked the little packages back inside and laid the branch under the tree in the hopes that the young would continue to develop, whatever they were, and headed inside to do some research. Here’s what I learned.
Leafcutter Bees in the Megachile genus are solitary bees that are known for neatly cutting bits of leaves or flower petals to build the cells of their nests. They will sometimes build these nests within a hollow branch, as the ones in my garden did, but more often they build them in burrows in the ground. Wherever they are built, the nests are arranged in a long column of cells. In each cell, the female places an egg and a supply of food, usually pollen. About a week after I found these nests, I discovered a bee busily adding a new cell and cap to one of the hollow branches.
Once the egg hatches, it eats the food, molts several times, spins a cocoon, and pupates. It takes months before the adult bee emerges. Male Leafcutter Bees die shortly after mating. The females live a few weeks longer, allowing them time to build their nests. While they are alive and buzzing around, they pollinate the local plants. In my garden alone, I have spotted them feeding on Reseda sp., Schouwia purpurea, Capparis sp., and Echinops sp.
The authors of Gardens of a Sacred Landscape state, “Recently hives of domesticated social honeybees have been brought in from Egypt, and scientists are worried about their impact on the wild bees, and hence on the efficiency with which native plants are pollinated.” The book was published in 2008 and unfortunately I have not found any other research (in English) about this issue.
Sadly, there is a research study about Leafcutter Bees that are using plastic and other synthetic material to build their nests.