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Purple Paradise
If you want to attract insects to your garden, plant an artichoke and let it flower.
You'll get honey bees, syrphid flies, butterflies, carpenter bees and leafcutter bees. (And well, a few predators, such as spiders and wasps.)
Today we saw leafcutter bees (Megachile spp.) tumbling in the purple strands, looking so much like residents of a gated community. A purple gated community.
These native bees, so named because they cut fragments from leaves and bring them back to line their nests, are excellent pollinators. They nest in our bee condo, just inches away from the artichoke plants.
Then we saw a male cuckoo leafcutting bee (below), genus Coelioxys, as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis. "The females hide their eggs between the leaves in Megachile nests and their larvae kill the host egg or larva and complete their development on the pollen provided by the host female," he said.
With Megachile, if you provide a bee condo (a wood block drilled with holes), you may see these tiny insects provisioning their nests. (See the list of resources provided by Thorp, on the Harry H. Laidlaw Jr. Honey Bee Research Facility website.
All in all, leafcutter bees are a star attraction for National Pollinator Week, which began Monday, June 18 and continues through Sunday, June 24.
Male cuckoo leafcutting bee (genus Coelioxys) emerges from the purple strands of an artichoke blossom. (Photo by Kathy Keatley Garvey)
Male cuckoo leafcutting bee (genus Coelioxys) walking on an artichoke blossom. (Photo by Kathy Keatley Garvey)
Bed Check!
All winter long my bee condo housed 16 tenants...and one earwig.
And quite comfortably, too, thank you.
It all began last fall when the leafcutting bees laid their eggs, provisioned each nest with a nectar/pollen ball, and plugged it with leaves.
Just about every morning, I did a bed check. Yes, 16 tenants and one earwig. (In actuality, there were probably more of those nasty little earwigs, but each time I checked, I found only one. But lots of frass!)
Bee condos are really just wood blocks drilled with tiny holes for native bee nests.
In late April and early May, the tenants began to stir. As of yesterday, 13 holes had popped open. Ah, emergence! The nocturnal earwig? Nowhere in sight.
You, too, can rear leafcutting bees (Megachile spp.) in your yard. All you need is the housing, which you can buy at most beekeeping supply stores or online. You can also go online and buy the plans to build them.
Senior conservation associate Matthew Shepherd of The Xerces Society for Invertebrate Conservation, in his fact sheet about native bee nesting sites, wrote: "There are 4,000 species of native bees in North America. Together they form the most important group of pollinators. Like all wildlife they are affected by changes in our landscapes, especially the loss of nesting sites. Bees make nests in which they create and provision brood cells for their offspring. In many modern landscapes, a desire for neatness has usually resulted in the removal of bare ground, dead trees, and untidy corners of rough grass—all important nesting sites for bees."
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, has provided a list of resources for native bee nesting requirements. It's available free on the Harry H. Laidlaw Jr. Honey Bee Research Facility website.
And, the Xerces Society recently published a Pollinator Conservation Handbook where you can find more information about our pollinators.
Just don't expect all your tenants to be pollinators, and all your pollinators to be tenants.
Newly emerged leafcutter bee outside her nest. (Photo by Kathy Keatley Garvey)
One leafcutter bee is tucked in head first; the other is ready to leave. (Photo by Kathy Keatley Garvey)
An Uncommon Bee
Sometimes you get lucky.
While watching floral visitors foraging last week in our rock purslane (Calandrinia grandiflora), we noticed a tiny black bee, something we'd never seen before.
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the UC Davis Department of Entomology, identified it as a female leafcutting bee, Megachile gemula, "which has an all-black form."
It's a rather uncommon bee, but a distinctive bee, said Thorp, who is one of the instructors of The Bee Course, offered every year in the Southwestern Research Station, Portal, Ariz., for conservation biologists, pollination ecologists and other biologists who want to gain greater knowledge of the systematics and biology of bees. Participants come worldwide to learn about bees.
Megachile gemula is native to the United States. The females snip round holes in leaves and line their nests with the material. From egg to larva to pupa, a new generation emerges from the sealed nest.
Meanwhile, if you want to go on a walking tour with Thorp, mark your calendar for Friday, June 22. Thorp will lead a Tahoe National Forest Service tour of native plants and pollinators in the Loney Meadow, near Nevada City, Nevada County. The tour, free and open to the public, will take place from 10 a.m. to approximately 2 p.m.
The walk is provided as part of the Forest Service Pacific Southwest Region’s 2012 Pollinator Special Emphasis Area "which has been developed to call attention to the importance of butterflies and native bees in providing important services for food production and ecosystem health," said Kathy Van Zuuk, Yuba River Ranger District botanist and forest level non-native invasive plant coordinator.
And what bees might tour participants encounter? Probably bumble bees, mining bees, digger bees, leafcutting bees, mason bees and cuckoo bees, Thorp said. Other floral-visitors are expected to include flies, butterflies, and beetles, he said. Van Zuuk and fellow botanist Karen Wiese will identify the native plants.
Those interested should meet at 10 a.m. at the Sierra Discovery Trail parking lot located off Highway 20 to carpool to Loney Meadow (where parking is limited). Participants of all ages should bring water, snacks, insect repellent, sunscreen and wear suitable footwear. (No dogs, please.)
Further information is available by contacting Van Zuuk at (530) 478-6243 or emailing her at kvanzuuk@fs.fed.us.
Female leafcutting bee, Megachile gemula, on rock purslane. (Photo by Kathy Keatley Garvey)
Female leafcutting bee, Megachile gemula, exiting rock purslane. (Photo by Kathy Keatley Garvey)
Hole in One
First you give them roots, then you give them wings.
That's what's happening in our bee condo, a wooden block (nest) with drilled holes for leafcutting bees (Megachile).
They flew in, laid their eggs, provisioned the nests with pollen and leaf fragments, and capped the holes.
We had 11 tenants. Now there's a hole in one.
Success! A leafcutting bee emerged. Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, says that "Some leafcutting bees, especially the introduced ones like the alfalfa leafcutting bee, have more than one generation per year. Bees of the second and third generation may clean out or partly clean out old nest holes like this and construct a new nest inside. Sometimes you can find new leaf material inside the old cocoon of the previous nest builder. Thus, the tunnels get smaller in diameter with succeeding generations. Kind of like the build up of old cocoons in honey bee comb and resulting smaller inner diameter of the brood cells in old dark comb."
It's all rather exciting being a "beekeeper." We've never had a hole in one--'til now.
If you, too, want to keep native bees, Thorp has compiled a list of where you can buy homes for them or where you can learn how to build your own. The list is on the Harry H. Laidlaw Jr. Honey Bee Research facility website.
You can also buy them at beekeeping supply stores.
Now that we have a hole in one, 10 tenants to go...
Hole in one--a hole signifying the emergence of a leafcutting bee (Megachile). (Photo by Kathy Keatley Garvey)
Leafcutting bee provisioning her nest. (Photo by Kathy Keatley Garvey)
Leafcutting bee on sedum. (Photo by Kathy Keatley Garvey)
Ten Tenants
Ten tenants.
That's how many tenants are occupying our wooden bee block, aka "bee condo."
It's "home, sweet home" for leafcutting bees (Megachile spp.).
Daily we see these native bees tear holes in leaves (red bud, rose, catmint, gold coin, rock purslane and nectarine) and gather the fragments to line their nests.
Folks who grow prize-winning roses--the kind that win blue ribbons at county fairs and rose shows--aren't fond of these little critters, but we are.
Especially when we see two leafcutters at the bee condo at the same time...
Two leafcutting bees (Megachile spp.) at their bee condo. (Photo by Kathy Keatley Garvey)
Leafcutter bee sipping nectar from a rock purslane. (Photo by Kathy Keatley Garvey)
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