On Native Loosestrife and Oil Bees


Oil bees? What the heck are oil bees? Those were my first thoughts when I heard of them for the first time. There are something like 320 species of oil bee in this world, each with their own interesting ecology. These solitary Hymenopterans seek out specific flowers that produce special oils which these bees mix with pollen to feed their developing young. Some even go as far as to use the oils to line their nests. 

Surely these bees must be tropical. I really couldn't imagine this interaction going on up here in the temperate zones. You can imagine my surprise then when I found that there are oil bees and the plants they require haunting some of my favorite hiking spots. As it turns out, some of our native loosestrifes in the genus Lysimachia produce such oils. 

What's more, the bees that utilize them are quite specialized. They all hail from the same genus - Macropis. Female Macropis dig their nests into the ground. Using their highly tuned senses, these solitary bees search far and wide for species of loosestrife that can provide the oils they need. The whorled loosestrife (Lysimachia quadrifolia) is one such species. If you look closely, you can see that the inside of the flowers are streaked with dark resin canals. 

Luckily for the oil bees, this species seems to be quite adaptable as far as habitat goes. I see it most often lining trails and service roads. Mature plants create quite the spectacle with their tall stature, whorled leaves, and sprays of yellow flowers. I will have to pay close attention to these blooms over the next couple of weeks in hopes of seeing the oil bees that share such a close relationship with it. 

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