- Author: Kathy Keatley Garvey
It's a beautiful morning and life is good.
A male leafcutter bee (genus Megachile) drops down on a spent flower in a Vacaville pollinator garden.
He's warming his flight muscles, ready to greet the day--and maybe a female of his species.
Mr. Leafcutter Bee does not see the long-legged, long-beaked predator stalking him. The predator, a ringed assassin bug, Pselliopus cinctus, is hungry.
A bee breakfast would be good. Mr. Assassin Bug's menu over the last week probably included aphids, a leafhopper, a a lacewing and maybe a lygus bug or caterpillar. And now, maybe, a bee? He's focused on ambushing and stabbing the unsuspecting bee, injecting his venom and sucking out the body contents. That's what assassin bugs do, and he's an assassin bug. He's one of some 7000 species of assassin bugs found throughout the world.
Assassin bugs (Reduviidae) “are one of the largest and morphologically most diverse groups of Heteroptera, or true bugs,” according to a UC Riverside site, Heteropteran Systematics Lab.
The predator-prey drama lasts for about a minute. Abruptly, the bee spots danger and buzzes off.
It was a good morning for the leafcutter bee and a bad morning for the assassin bug. But the day isn't over…
- Author: Kathy Keatley Garvey
The narrowleafed milkweed, Asclepias fascicularis, beckons monarch butterflies (the host plant), aphids, praying mantids and assorted other insects, but once in a while, you'll see a leafcutter bee. Both the plant and the bee are natives.
This male bee (below) spent the afternoon patrolling for females, but it rested in between.
It's a dangerous place to rest when there's a predator (praying mantis) around, but all ended well.
Leafcutter bees, spp., so named because the females cut leaves and petals (perfectly round holes!) to line their nests, are smaller than honey bees--and much faster. They're easily recognizable by the black-white bands on their abdomen.
The females do all the work. They gather pollen and nectar, make the nests from the leaf and petal fragments, and lay eggs. They seal the egg chambers with the leaves or flower petals.
The male's job is to reproduce. And sometimes, you'll see one sunning itself on a milkweed leaf.
Of the 4000 bee species known in the United States, about 1600 reside in California. The leafcutter bee is just one of them. The family, Megachilidae, includes these leafcutting bees, Megachile angelarum, M. fidelis and M. montivaga; the alfalfa leafcutting bee, M. rotundata; the Mason bee, Osmia coloradensis; and the blue orchard bee (BOB), Osmia lignaria propinqua.
For more information on California's bees, read California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday), the work of UC-affiliated scientists,
/span>- Author: Kathy Keatley Garvey
Day 5 of National Pollinator Week: Meet the leafcutter bee, family Megachilidae.
It's a native pollinator, a solitary bee, and about the size of a honey bee.
Its coloration--the black-and-white banded abdomen--makes it easily recognizable.
As the name suggestions, they (the females) cut circular holes in leaves to line their nests for brood-rearing. Rosarians who enter their roses in competition aren't fond of them because of the "imperfections" in the leaves. A hole in one--or holes in many--aren't going to give them a whole lot of blue ribbons.
But having leafcutter bees in your garden is a joy. They're good pollinators and gentle bees. Leafcutter bees carry pollen on the underside of their abdomen, not on their hind legs like honey bees, do. Agriculturists manage the alfalfa leafcutter bee (Megachile rotundata) for crop pollination.
Leafcutter bees nest in natural cavities, mostly holes in soft wood or in hollow, pithy plant stems. You can also create bee condos or housing for them, drilling specific-sized holes in a block of wood.
We saw this little male Megachile foraging on Verbena. He paused for a few minutes and then took flight. Things to do and places to go...
- Author: Kathy Keatley Garvey
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.
- Author: Kathy Keatley Garvey
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.