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Insect of the Week: Leafcutter Bee
January 21, 2016
Bees and wasps, generally speaking, are my favorite insects. I love their busyness. I love that they pollinte my flowers and vegetables. I love watching them pick through flowers.
When most people think of bees they think of honey bees. That's logical as it is the species we most often see in popular culture or read about in the news.
However, they are far from the most common bee in my yard. In fact, honey bees were introduced to North America by Europeans several hundred years ago. We have become so reliant on them because commercial growers, who need extremely high concentrations of bees in order to pollinate their crops, have generally used honey bees for this service. I have never asked anyone "why" specifically, but I presume the fact they live in colonies makes it easier to keep track of them and transport them where needed. Figures vary, but I've read that more than 25 percent of our diet is connected to honey bee pollination.
Out in my yard I see several dozen varieties of bees. I do have a fair number of honey bees present at any one time, but I have never seen a hive. Honey bees can travel several miles in search of flowers. But one of the most common bees I see are called leafcutter bees.
Have you ever seen the bee "houses" sold in magazines or at a gardening store that look like they have a lot of holes? Those are houses intended to attract
leafcutter and mason bees. The bee house pictured here is for mason bees, but a leafcutter house is quite similar. The tubes are just slightly smaller based on the preference of the bees.
Leafcutter bees, which are active in the summer, and mason bees, which are active in the spring, are solitary bees meaning that they live alone. They don't live in a colony. Instead of a hive, females lay eggs in holes, any place they can find them - in logs, in cracks on the outside of your house, in the ground, in hollow reeds of dead plants, etc.
They are called leafcutter bees because they cut perfect little circles out of plants like roses and lilacs. They use that small piece of leaf to create a little chamber within their nesting hole for an egg and pollen to feed the baby bee when it emerges from its egg. They then start the process again, getting more pollen and another piece of leaf to create another chamber for another egg right on top of the previous one. When they are finished, a six inch hole in the ground or one of the reeds from a bee house could have eight eggs within it.
I've seen those perfect little holes in my rose leaves for years and always wondered what "pest" was doing it. Turns out, it wasn't a pest at all, but I was helping to provide nesting material for one of the "good guys" in my garden. I plan to put in at least one more rose bush for them to use this summer.
The idea behind the bee houses is to give the bees more places to reproduce, and - if you want to take the time - you can use these houses to help protect the baby bees from harm, including parasitic wasps who inject their own eggs into the cocoons of the growing bees in order to provide a live food source for the wasp larvae when they hatch from their own eggs. That's nature for you!
What is most incredible about leafcutter and mason bees is that they are considered better pollinators than honey bees. Honey bees attach pollen from flowers to their hind legs, giving them the appearance of carrying around big yellow bags. They use their saliva to hold the pollen in place, and so they lose very little pollen while visiting flowers. On the other hand, leafcutter bees carry pollen on the hairy undersides of their abdomen. They get pollen everywhere as they go from flower to flower, which is what the flowers love. A handful of leafcutter bees can do the same amount of pollinating as many times more honey bees.
In addition, leafcutter bees are much less aggressive than honey bees. It is unlikely that one will sting you unless you are really aggravating it.
Fruit tree growers love mason bees in particular because they are more efficient than honey bees and they emerge in the spring right when fruit trees are ready to be pollinated.
This summer I am building a bee house for leafcutter bees. I ordered "nesting holes" for leafcutter bees and 100 leafcutter bee cocoons that will emerge ready to pollinate in June. I did not order any additional mason bee cocoons because I don't think I will have enough blooms early in the spring to feed all of them, but I did order some nesting reeds for the handful of mason bees I think are in my yard already.
I purchased these materials from www.CrownBees.com, which is also where I got the photo of the bee house in this blog post. It is a great site for learning more about our native species of bees, including mason bees, leafcutter bees and bumblebees, which are also prolific in my yard.
I am quite excited to see the leafcutter bees emerge and examine the activity as they create their next generation in the bee houses I put up throughout my yard. I already have a large amount of bee activity, thanks to all my perennial plants and vegetables, but I'm going to be sure to put in a few more this year to provide enough food for my new bees.
I'm busy working on my blog posts. Watch this space!