Posts Tagged: Robbin Thorp
A field of green ribboned in yellow.
Anyone who drives down Pedrick Road in Dixon, Calif., and sees the spectacular sunflower fields can't help but smile.
Yellow sunflowers do that to you. They make you smile.
A native of the Americas and the state flower of Kansas, the sunflower (Helianthus annuus) brightens gardens and run-down neighborhoods, but when it's planted in rows and each head turns toward the sun, it's like a thousand suns and a thousand smiles.
Add honey bees and native bees, and nature's canvas is complete.
If you visit a sunflower field early in the morning, you might see male long-horn bees, genus Melissodes, sleeping in aggregations, on the heads.
As native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, points out: "Males of native solitary bees do not have nests to return to at night as the females do. So they fend for themselves in a variety of different ways such as these sleeping aggregations, or within tubular flowers that close up each day, like squash bee males do in squash flowers."
That's bee heaven.
Honey bee foraging on sunflower in a field off Pedrick Road, Dixon. (Photo by Kathy Keatley Garvey)
Dixon, Calif. farmland ablaze with sunflowers. (Photo by Kathy Keatley Garvey)
Close-up of sunflowers. Just add bees. (Photo by Kathy Keatley Garvey)
Head's up! A lone sunflower head towers above the field as bees buzz toward to it. (Photo by Kathy Keatley Garvey)
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)
When you install bee condos--those wooden blocks with holes drilled in them to attract nesting native bees--sometimes you get the unexpected.
Home invasion! Home invasion!
We installed two bee condos, each about the size of a brick, in our yard. One is for leafcutting bees (genus Megachile) and is filled quite nicely, thank you, with 10 tenants. Another, with larger holes, is for blue orchard bees (BOBs, genus Osmia). Despite our "vacancy" sign (discounted rates, free WiFi, free continental breakfasts), nothing is occupying it except earwigs.
Earwigs! We're wigged out.
They were especially persistent in the damp weather.
Native bee guru Robbin Thorp, a native pollinator specialist and emeritus professor of entomology at the University of California, Davis, who has researched native bee holes with colleagues John Barthell and Gordon Frankie, told us: "We found that mostly wasps and earwigs occupied the largest holes. Only a few of the introduced leafcutting bees that could not find appropriate size holes when bee populations were abnormally high would make aberrant nests in the larger cavities. By 1990, we scaled back to the three diameters that our bees use: 4.5, 6.5 and 8 mm (3/16, 1/4, and 5/16 inch) for our studies in California."
The earwigs, Thorp says, "are not so likely to be present now that the weather is hot and dry, but in shady, damp, cool areas, and especially early in the year when it is wet and cool, they can be a problem."
Their research, published in Environmental Entomology in 1998 and titled “Invader Effects in a Community of Cavity Nesting Megachilid Bees (Hymenoptera: Megachilidae)” involved native bee species and their introduced competitors.
In their paper, they wrote that the European earwig (Forficttla auricularia L) from Eurasia and northern Africa, was introduced into North America at the turn of the century. "It has invaded most counties in the state of California since its apparent introduction in the late 1910s (Essig 1923, Langston and Powel! 1975)," they wrote. "Its populations have grown to high numbers in natural areas, especially in riparian zones where humidity levels are relatively high (Barthel! and Stone 1995). The earwig is most active during evening hours, climbing into tree crowns to scavenge and hunt but hiding in cracks, crevices, or holes during the daylight hours."
Active indeed. Those European earwigs soon found our condo for BOBs (which perhaps should now mean Big ol' Blast).
Earwig inside a blue orchard bee condo, which has larger holes than one for leafcutting bees. (Photo by Kathy Keatley Garvey)
This bee condo for leafcutting bees has 10 tenants. It is about the size of a brick and has smaller holes than a bee block for blue orchard bees. (Photo by Kathy Keatley Garvey)
Leafcutting bee provisioning her nest. (Photo by Kathy Keatley Garvey)
Gotta love those dragonflies in the family Libellulidae.
The Thunderbirds of the insect world, they perform amazing aerial maneuvers as they skim over water, catching mosquitoes, knats, flies and other undesirables on the wing.
But oh--occasionally they nail a pollinator.
A red flame skimmer (Libellula saturata) skimmed over our fish pond and pool last Saturday and picked on the pollinators. Well, at least one pollinator.
It grabbed a female sweat bee, of the genus Halictus, probably H. tripartitus (as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis, and Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis).
Yes, they can even identify a mangled sweat bee in the mouth of a dragonfly.
And no sweat bee.
Flame skimmer munches on a female sweat bee of the genus Halictus. (Photo by Kathy Keatley Garvey)
Flame skimmer is long and lean with huge compound eyes. (Photo by Kathy Keatley Garvey)
Oh, to go through life being called a "short fat fly."
Such is the case with a specific tachinid fly (family Tachinidae, genus Gymnosoma), which we spotted on a coreopsis (aka tickseed) growing along a Fort Bragg cliff.
It's an odd-looking fly. Its abdomen resembles a ladybug or lady beetle. Its head--definitely a fly. (Gymno is Greek for naked, and soma means body.)
"Its larvae are parasites on stink bugs," said native polliantor specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis.
Check out another image on bugguide.net.
Well, it's good that this ladybug mimic rids the world of a few more stink bugs!
Short fat fly (genus Gymnosoma) on coreopsis at Fort Bragg. (Photo by Kathy Keatley Garvey)
The larvae of this "short fat fly" feed on stink bugs. (Photo by Kathy Keatley Garvey)