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The Leafcutter Bee–A Stealth Pruner

Leafcutter bee damage toned_3326Every morning there was new damage. Something was demolishing my garden, leaving the foliage in lacy tatters. At first I thought it might be the work of cutworms, but I never saw cutworm sign—neither caterpillars nor their droppings. The damage didn’t look like the random chompings of hungry caterpillars either. Each wound was a nearly perfect semicircle, cut with precision, ruining the shape of the leaf.

I’m very proud of my courtyard garden with its pots of succulents, yellow bells, blue ruellia and plumbago. I’d never considered myself a gardener, but here in the entryway to my Arizona home, I’ve had a few successes. It was frustrating to see some of my plants being decimated. Whatever was responsible for the damage seemed to favor the plumbago and the yellow bells, among my favorites.

Leafcutter ants often attacked the lantana in the front yard, but they seemed to prefer the flowers. I could tell the leafcutter ants had been active when I saw their anthills encircled by tiny yellow florets from the lantana blossoms.

This damage was caused by some other creature. A stealth pruner was snipping the greenery from my favorite plants. After weeks of puzzlement, I solved the mystery. I searched for leafcutters common to Arizona and found the culprit—the leafcutter bee (Megachile spp.)

This solitary bee, a native species, is an important pollinator in the western United States. The leafcutter bee nests in soft plant stems or rotted wood, creating cells for its larvae from the leaf remnants it cuts and carries home. The bee fills each leafy cell with food—pollen and nectar—to nourish the young-to-be. When a cell is laden with food, the female bee (who does all of the work) lays a single egg and seals the cell. The young bees hatch the following season.

Insecticides are not effective against these creatures, as the bees don’t eat the leaves. Since bees are vital pollinators, most people put up with the tattered plants or cover the bees’ favorites with a cheesecloth barrier.

Now that I knew who the culprits were, I had to see them in action. I stalked them for several days, without success. Then on a hot, sunny afternoon in late May I finally caught one in the act. A small insect with a flat, black-and-white-striped abdomen and a set of sharp jaws was doing the damage. The leafcutter bee was unassuming looking, but capable of mincing my plants to pieces. Once I knew what to look for, I saw many more of these quick, efficient pruners.

Each bee would circle a plant, as if looking for a leaf turned just so. Once satisfied with the angle of repose, the bee would swoop toward the leaf and in a matter of seconds slice off a semicircular piece of greenery—rolling the slice into a cylinder that the insect would grasp in its legs. When the cylinder dangled from the last thread of plant tissue, the bee would take off, pulling the tube of green with it.

The act of pruning required so much agility and precision, I had to forgive the bees for cutting such a swath through my garden. Nature will have her way, and this time I’ll just sit back and watch in wonder.

Leafcutter Bee in Action Leafcutter Bee in Action Leafcutter Bee in Action Leafcutter Bee in Action Leafcutter Bee in Action Leafcutter Bee in Action

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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© 2014 by Susan E. Swanberg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Photographs by Susan E. Swanberg. ©2014.

For more about these bees see:

http://www.fritzhaeg.com/garden/initiatives/animalestates/animals/leaf-cutter-bee_text.html

http://ag.arizona.edu/yavapai/anr/hort/byg/archive/solitarybees.html

http://cals.arizona.edu/urbanipm/pest_press/2005/april.pdf

 

 

 

 

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