Email Print Site Map
Cooperative Extension San Joaquin County
University of California
Cooperative Extension San Joaquin County

Posts Tagged: Robbin Thorp

Hide the Cactus!

Hide the cactus! There's a Mexican cactus fly in our midst.

A large black fly hovers over a Mexican sunflower (Tithonia) in our bee garden and then drops down to sip some nectar. At first glance it looks like a carpenter bee but this one hovers like a syrphid fly, aka flower fly or hover fly.

"Hover fly," I say.

Entomologists Martin Hauser, Lynn Kimsey and Robbin Thorp quickly identified the critter.

Hauser, senior insect biosystematist with the Plant Pest Diagnostics Branch of the California Department of Food and Agriculture, says it's in the genus Copestylum (with over 350 species in the new world) and figured it to be the species,  mexicanum, commonly known as the Mexican cactus fly.

Said Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis: "Nice, this is actually a kind of syrphid flower fly, better known as a cactus fly. The larvae breed in rotting cactus tissue."

Native pollinator specialist Robbin Thorp, emeritus professor of entomology, also figured it to be a Mexican cactus fly, Copestylum mexicanum.  "It's commonly known as a cactus fly (Syrphidae, Tribe Volucellini).  "It used to be in the genus Volucella, But now it's in the genus Copestylum."

This fly is not small. It's about 3/4 of an inch long. It lays its eggs in rotting plant material "and they really like rotting cacti," Hauser commented. "As far as I know, they only go into dying cacti and do not attack healthy cacti…. But there is actually not much known about their biology."

The resident cacti expert at our house is worried, showing his best prickly pear expression. He quickly canvasses the yard. Whew! No rotting cacti. All thriving and in good health.

So far, so good...

Black hover fly, aka Mexican cactus fly, sipping nectar from a Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)
Black hover fly, aka Mexican cactus fly, sipping nectar from a Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)

Black hover fly, aka Mexican cactus fly, sipping nectar from a Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)

Side view of the black syrphid fly, a Mexican cactus flower. (Photo by Kathy Keatley Garvey)
Side view of the black syrphid fly, a Mexican cactus flower. (Photo by Kathy Keatley Garvey)

Side view of the black syrphid fly, a Mexican cactus flower. (Photo by Kathy Keatley Garvey

Mexican cactus fly ready to take off. (Photo by Kathy Keatley Garvey)
Mexican cactus fly ready to take off. (Photo by Kathy Keatley Garvey)

Mexican cactus fly ready to take off. (Photo by Kathy Keatley Garvey)

Posted on Tuesday, September 30, 2014 at 5:29 PM

Quit Mimicking Me!

Last weekend a little critter made its first-ever appearance in our family bee garden. It was neither a grand entrance nor a grand insect.   

"A fly!" I thought, as I looked at its knoblike bristle or arista on the end of each antenna.

But its body--what little I could see of it before it winged out of there--definitely resembled a wasp. A Western yellowjacket (Vespula pensylvanica) or European paper wasp (Polistes dominula).

Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the UC Davis Department of Entomology and Nematology, identified it as a syrphid fly, genus Ceriana, family Syrphidae. 

Talented Davis photographer Allan Jones captured an excellent photo of Ceriana in 2012. A full body shot: head, thorax and abdomen! His excellent image (second one, below) shows the distinguishing characteristics: two wings (fly), not four wings  (bees, wasps), as well as the arista (fly) and the spongelike mouthparts (fly).

BugGuide.Net posted some excellent images of Ceriana on its site. Class: Insecta. Order, Diptera. Family: Syrphidae: Genus: Ceriana.

Ceriana is a genus of wasp mimics. Basically, it's a syrphid fly, a pollinator. It's also known as a hover fly or flower fly as it hovers, helicopterlike, over flowers before drops down to forage.

Would-be predators, no doubt, avoid Ceriana because of its coloration. "Oops, don't mess with that! That's a wasp!"

Picnickers who don't know a faux wasp from a real one would probably run from it, or swat at it.

"It's definitely a good mimic and probably gets a lot of protection from that coloration," said Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis.

So true!

This wasp mimic is actually a fly, genus Ceriana. (Photo by Kathy Keatley Garvey)
This wasp mimic is actually a fly, genus Ceriana. (Photo by Kathy Keatley Garvey)

This wasp mimic is actually a fly, genus Ceriana. (Photo by Kathy Keatley Garvey)

Davis photographer Allan Jones captured this fantastic  image of the wasp mimic, Ceriana. (Photo by Kathy Keatley Garvey)
Davis photographer Allan Jones captured this fantastic image of the wasp mimic, Ceriana. (Photo by Kathy Keatley Garvey)

Davis photographer Allan Jones captured this fantastic image of the wasp mimic, Ceriana. (Photo by Kathy Keatley Garvey)

This is a Western yellowjacket, Vespula pensylvanic, which looks a lot like the wasp mimic, genus Ceriana. (Photo by Kathy Keatley Garvey)
This is a Western yellowjacket, Vespula pensylvanic, which looks a lot like the wasp mimic, genus Ceriana. (Photo by Kathy Keatley Garvey)

This is a Western yellowjacket, Vespula pensylvanic, which looks a lot like the wasp mimic, genus Ceriana. (Photo by Kathy Keatley Garvey)

This is a European paper wasp, Polistes dominula. A syrphid fly mimics this. (Photo by Kathy Keatley Garvey)
This is a European paper wasp, Polistes dominula. A syrphid fly mimics this. (Photo by Kathy Keatley Garvey)

This is a European paper wasp, Polistes dominula. A syrphid fly mimics this. (Photo by Kathy Keatley Garvey)

Posted on Monday, September 8, 2014 at 6:07 PM

About Those Sleepovers...

We're receiving lots of inquiries about sleepovers ever since we began posting images of male longhorned bees, Melissodes agilis, sleeping on our lavender.

Boys' Night Out!

While the females sleep in their underground nests, the males cluster on stems. No, they don't have pillow fights or nightcaps but they do wiggle around a lot until they get comfortable.

Now the boys have moved from their favorite spot on the lavender (vertical sleepover) to the guara (horizontal sleepover). We suspect this may be due to several reasons: (1) The presence of three praying mantids in the lavender (2)  the lavender is fading while the guara is flourishing and (3) the guara offers a definite height advantage, which may deter a few predators (but not birds).

Nevertheless, the boys start arriving for their nightly sleepover around 5 p.m. and don't budge until around 7 p.m., sometimes as late as 9 or 10.

One reader asked some interesting questions.

"There is a nightly cluster of boys on an aster stem in my front yard and I wanted to find out more about them. In particular, do they/can they/will they sting?"

No, boys don't sting--just the girls. As native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, explains: "Boy bees cannot sting.  They lack a stinger which is a modified ovipositor in their wasp ancestors.  Occasionally a girl bee may spend the night out if she is caught by sudden drop in temperature.  Usually she will not be part of a group sleep over.  So don't attempt to handle unless you are confident you can tell boy bees from girl bees or they are too sleepy to defend themselves."

The reader also asked: "Typically how close to the girls' nest(s) do the boys' slumber? I want to try and make sure I don't touch it when planting at end of summer."

Says Thorp: "Boy sleeping aggregations are based on a suitable perch and not related to where females are nesting, but probably no more than 100 yards from the nearest female nest.  Females nest in the ground and have rather distinctive round holes about the diameter of a pencil or slightly smaller, sometimes with small piles of dirt around them looking like mini-volcanos.  The holes may be widely separated or clustered together depending on the species, but each female digs her own burrow."

Of course, not all slumbering bees in this area are Melissodes agilis,  as Thorp points out. Some may be other species of the genus Melissodes and some may belong to the closely related Svastra obliqua.

The reader also wondered: "When watching the boys tonight, about ten of them started waking up and kicking each other. They finally settled down and started to nestle back in for the 'night'--it was only 6 p.m.--but I wasn't sure if my presence was getting them riled or they tend to act like kids sharing a bed?"

Says Thorp: "The boys usually settle in as the light dims in the evening.  Cool, and drizzly conditions may modify bed time.  Each establishes his own spot, so there may be some jostling for position initially."

We've noticed that, too. We've also noticed that the early morning risers--the carpenter bees, bumble bees, honey bees and syrphid flies--work around the slumbering Melissodes agilis. All that buzzing must sound like the human version of a chainsaw. "Will ya shaddup, already? Can't you see we're trying to sleep?"

Once the boys awaken, though, watch out! They'll dive-bomb the pollinators or any critter working or resting on "their" flowers.  They're very territorial and determined to save the food source for the females of their species. The butterflies, including the Western tiger swallowtail, anise swallowtail, Gulf Fritillary and cabbage whites, don't linger when the boys target them.

And speaking of California bees, we're eagerly awaiting the arrival of the book, California Blooms and Bees: an Identification Guide for Gardeners and Naturalists. It's co-authored by research entomologist/professor Gordon Frankie of UC Berkeley; Thorp (who received his doctorate from UC Berkeley); and their UC Berkeley affiliates, photographer/entomologist Rollin Coville and floral/herbarium curator Barbara Ertter.

More than 1600 species of undomesticated bees call California their home. The authors focus on 22 of the most common genera and the flowers they frequent.

Meanwhile, you'll want to check out Frankie's UC Berkeley Urban Bee Lab website to read more about native bees and his exciting research.

Male longhorned bees jockeying for position on a guara stem. (Photo by Kathy Keatley Garvey)
Male longhorned bees jockeying for position on a guara stem. (Photo by Kathy Keatley Garvey)

Male longhorned bees jockeying for position on a guara stem. (Photo by Kathy Keatley Garvey)

Not every stem is taken and not all the males cluster six or seven to a stem. These two appear to want space. (Photo by Kathy Keatley Garvey)
Not every stem is taken and not all the males cluster six or seven to a stem. These two appear to want space. (Photo by Kathy Keatley Garvey)

Not every stem is taken and not all the males cluster six or seven to a stem. These two appear to want space. (Photo by Kathy Keatley Garvey)

This male Melissodes agilis, is sleeping solo on a guara blossom. (Photo by Kathy Keatley Garvey)
This male Melissodes agilis, is sleeping solo on a guara blossom. (Photo by Kathy Keatley Garvey)

This male Melissodes agilis, is sleeping solo on a guara blossom. (Photo by Kathy Keatley Garvey)

Posted on Monday, July 28, 2014 at 10:01 PM

Bumble Bees and Spiders Don't Mix?

Bumble bees and spiders don't mix, you say?

Well, they will at the Bohart Museum of Entomology's open house from 1 to 4 p.m., Saturday, July 26. The family-centered event, free and open to the public, takes place in Room 1124 of the Academic Surge building on Crocker Lane, UC Davis campus.

Actually the theme is about spiders: "Arachnids: Awesome or Awful?" There you'll see black widow spiders, jumping spiders, cellar spiders and the like. But you don't have to "like" them as you do posts on Facebook!

You can also learn about bumble bees. Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, will be one of the tour guides.  Thorp co-authored the newly published Bumble Bees of North America: An Identification Guide, which is available in the Bohart gift shop. He can autograph your book and answer questions about how to attract bees to your garden.

Thorp was recently interviewed by Tom Oder of the Mother Nature Network on how to garden for bumble bees. So was Steve Buchmann, an adjunct professor in entomology and ecology at the University of Arizona.

Thorp told Mother Nature Network that some bumble bees are in very serious decline, and others are doing quite well.

So, how do you attract them to your garden? Buchmann was quoted as saying: “Gardening for bumblebees is similar to gardening for other bees and pollinators."  To entice bumblebees to visit your garden, “plant mints, Salvia, Monarda, plants in the sunflower family and clovers."

Read Oder's article for more information.

And keep your eyes open for the soon-to-be-published California Bees and Blooms: A Guide for Gardeners and Naturalists, co-authored by entomologist Gordon Frankie of UC Berkeley, Thorp, and two others with UC Berkeley connections: photographer/entomologist Rollin Coville and floral curator Barbara Ertter.

As for Saturday, July 26 there won't be a vote on whether you like bumble bees or spiders better, nor will you be asked to sing "Itsy Bitsy Spider" or "Baby Bumble Bee." It promises, though, to be fun and educational. Plus, you can enjoy the live  "petting zoo," featuring 24-year-old Rosie the tarantula, assorted walking sticks, and the colorful Madagascar hissing cockroaches. Yes, they hiss.

The gift shop is also popular. You can browse through the books, jewelry, t-shirts, sweatshirts, insect-themed candy, butterfly houses, and insect-collecting kits.

The Bohart Museum, directed by Lynn Kimsey, professor of entomology at UC Davis, houses nearly eight million insect specimens and is the seventh largest insect collection in North America. It is also the home of the California Insect Survey, a storehouse of insect biodiversity. Noted entomologist Richard M. Bohart (1913-2007) founded the museum.

 

The museum's regular hours are from 9 a.m. to noon and 1 to 5 p.m. Mondays through Thursdays. It's closed to the public on Fridays and on major holidays. Admission is free. For more information, email education and outreach coordinator Tabatha Yang at tabyang@ucdavis.edu or telephone her at (530) 752-0493.

A camouflaged jumping spider eyes a honey bee on Japanese anemone. (Photo by Kathy Keatley Garvey)
A camouflaged jumping spider eyes a honey bee on Japanese anemone. (Photo by Kathy Keatley Garvey)

A camouflaged jumping spider eyes a honey bee on Japanese anemone. (Photo by Kathy Keatley Garvey)

Robbin Thorp points at a yellow-faced bumble bee, Bombus vosnesenski. (Photo by Kathy Keatley Garvey)
Robbin Thorp points at a yellow-faced bumble bee, Bombus vosnesenski. (Photo by Kathy Keatley Garvey)

Robbin Thorp points at a yellow-faced bumble bee, Bombus vosnesenski. (Photo by Kathy Keatley Garvey)

Posted on Friday, July 25, 2014 at 9:12 PM

Karate Kick!

If you've ever watched a karate competition, you've probably seen the roundhouse kick, tornado kick, the reverse roundhouse kick or the flying side kick.

But have you ever seen a bee do that?

We were photographing sunflower bees on our Mexican sunflowers (Tithonia) yesterday, trying to catch the territorial dive-bombing. We were shooting with a Canon E0S 7D equipped with a 100mm macro lens. Settings: ISO, 1600. Shutter speed,  1/1400 of a second. F-stop, 10.

If bees could engage in humanlike conversation, imagine this dialogue:

"This flower is mine! Get off! I want my ladies to have that flower!"

"No, it's not! It's mine. I was here first! Leave me alone!"

For awhile, a large bee, a male longhorned bee, Svastra obliqua (as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis), appeared to be the "king of the mountain." It held its ground...er...floral resource.

Suddenly, faster than my shutter speed, a smaller bee of a different species, a male longhorned bee, Melissodes (probably Melissodes agilis, Thorp said) headbutted Svastra,  a scene reminiscent of a World Cup play.

One swift kick by Mr. Svastra and a surprised Mr. Melissodes shot straight up in the air, whirling end over end. 

Roundhouse kick? Tornado kick? Reverse roundhouse kicK? Flying side kick?

Whatever it was, the "bee master" won.

And he wasn't even wearing a black belt.

A male longhorned sunflower bee, Svastra obliqua, foraging on a Mexican sunflower. (Photo by Kathy Keatley Garvey)
A male longhorned sunflower bee, Svastra obliqua, foraging on a Mexican sunflower. (Photo by Kathy Keatley Garvey)

A male longhorned sunflower bee, Svastra obliqua, foraging on a Mexican sunflower. (Photo by Kathy Keatley Garvey)

A male longhorned sunflower bee, Melissodes agilis (right), targets the larger Svastra obliqua. (Photo by Kathy Keatley Garvey)
A male longhorned sunflower bee, Melissodes agilis (right), targets the larger Svastra obliqua. (Photo by Kathy Keatley Garvey)

A male longhorned sunflower bee, Melissodes agilis (right), targets the larger Svastra obliqua. (Photo by Kathy Keatley Garvey)

Melissodes agilis shoots straight up after a powerful kick by Svastra obliqua. (PHoto by Kathy Keatley Garvey)
Melissodes agilis shoots straight up after a powerful kick by Svastra obliqua. (PHoto by Kathy Keatley Garvey)

Melissodes agilis shoots straight up after a powerful kick by Svastra obliqua. (PHoto by Kathy Keatley Garvey)

Melissodes agilis (left) goes sprawling. (Photo by Kathy Keatley Garvey)
Melissodes agilis (left) goes sprawling. (Photo by Kathy Keatley Garvey)

Melissodes agilis (left) goes sprawling. (Photo by Kathy Keatley Garvey)

Posted on Monday, July 7, 2014 at 8:50 PM

Next 5 stories | Last story

Webmaster Email: mdhachman@ucdavis.edu