Jan. 27, 2011

Wool carder bees on salvia; photo taken Aug. 21, 2010 in Vacaville, Calif. Click to enlarge. (Photos by Kathy Keatley Garvey)

DAVIS--The European wool carder bee is not the terrorist that some folks think it is. 

The pollinator doesn’t cause colony collapse disorder (CCD). It’s not a newcomer to California. It doesn’t have five stingers. And it doesn’t target honey bees leaving behind a “blood-soaked battlefield.”

Entomologists at the University of California, Davis, are fielding a flurry of phone calls and emails as a result of a Sacramento-based news story gone viral.  A Sacramento resident  told an area TV station Jan. 24 that he discovered the first-ever European wool carder bee in California on May 23, 2009 and that it targets honey bees: it “cuts off their wings, cuts off their antenna, cuts off their heads, cuts off their torsi (tarsi) and stabs them to death.”  

It’s a pollinator and it does what pollinators do, say UC Davis entomologists.

“The species (Anthidium manicatum) was first collected in Sunnyvale, Calif. in 2007 and it was well established in the Central Valley by 2008,” said entomologist Lynn Kimsey, director of  the Bohart Museum of Entomology (home of more than seven million insect specimens, including wool carder bees) and professor and former interim chair of the UC Davis Department Entomology.

“Males are territorial and very aggressive, attacking any insect that enters its territory that isn't a wool-carder female,” Kimsey said. “The males establish territories around flowering plants, so they will attack honey bees and any other bees coming to visit the flowers.”

Neither gender has five stingers; the male has five spikelike projections on its abdomen that it uses to defend its territory.

“The number of honey bees that wool carder bees kills is probably no different than those honey bees lost to praying mantids, phorid flies and spiders,” said honey bee expert Eric Mussen, Extension apiculturist with the UC Davis Department of Entomology faculty.

Wool carder bee carding a catmint leaf. Photo taken Aug. 21, 2010 in Vacaville, Calif.

Wool carder bee nectaring catmint.This photo was taken Aug. 21 in Vacaville, Calif.

Wool carder bee on salvia; photo taken Aug. 21 in Vacaville, Calif.

Both the honey bee and the wool carder bee are exotic to North America. “Both species are native to southern Europe where they have interacted for thousands of years or longer,” Kimsey said.

So, she said, this is not a case of an invasive bee attacking and killing a native bee. Both are non-natives. European colonists brought the honey bee to what is now Virginia in 1622.  The wool carder bee was accidentally “introduced into New York state, presumably from Europe, before 1963,” according to research entomologist Tom Zavortink of the Bohart Museum. It was not purposefully introduced to pollinate alfalfa, as some reports allege.

Writing in a 2008 edition of the Pan-Pacific Entomologist, Zavortink and fellow entomologist  Sandra Shanks now of Port Townsend, Wash., pointed out that several papers “have documented its spread from neighboring areas in the northeastern United States and southern Canada” and that the species has since crossed the country. It was confirmed in Colorado in 2005, Missouri in 2006, and Maine, Michigan, Maryland and California (Sunnyvale) in 2007, the entomologists wrote.

“The first specimen of Anthidium manicatum that Sandy and I saw was collected in Davis on July 26, 2007,” Zavortink said.

Native pollinator specialist Robbin Thorp, emeritus professor of entomology, said a colleague collected wool carder bee specimens in Boise, Idaho, in June 2002.

“The bee was already present in Sacramento at least as early as 2007,” Thorp said. “I identified the bee from collections made by Gordon Frankie, UC Berkeley, during his urban garden studies there.” 

“Males have been observed and recorded to occasionally maim and kill honey bees, but they are no major threat to our primary agricultural pollinator,” Thorp said. “They do not aggressively seek out honey bees to do them intentional harm.   The male wool carder bee merely defends its territory from honey bees and other flying insects to keep the area free of potential competitors that might interfere with its mating opportunities. This non-native bee has co-existed with honey bees in Europe for hundreds of thousands of years.”    

“A. manicatum appeared this past summer in our Haagen-Dazs Honey Bee Haven (the half-acre  bee friendly garden planted next to the Harry H. Laidlaw Jr. Honey Bee Research Facility at UC Davis) but I have yet to see it maim or kill a honey bee,” Thorp said. “I am certainly not planning to recommend that we move our UC Davis Apiary from the area or take extraordinary means to protect our precious honey bees because of the presence of this relative newcomer.   Nor would I recommend we attempt to control or get rid of the ‘newbie.’  It is another pollinator, males visit flowers for nectar and females visit for pollen and nectar.”

The wool carder bee is so named because the female collects or cards plant hairs from leaves for her brood nest, which she constructs in convenient cavities such as old beetle holes and hollow stems, Thorp said. The bee’s plant preferences include lamb’s ear (Stachys byzantine, in the mint family Lamiaceae), a perennial grown for its fuzzy, silvery gray-green foliage. It’s also been collected in the figwort/snapdragon family (Scrophulariacae) and the pea and bean family (Fabaceae), according to the Zavortink-Shanks research.

The bee is mostly black and yellow. The females, about the size of a worker honey bee, range in body length from 11 to 13 millimeters, while the males are 14 to 17 mm.

The females have specialized hairs on their face to gather pollen grains. The males, substantially larger, can be aggressive in defending their territory, sometimes body-slamming honey bees and other insects to the ground.

Thorp said the wool carder bee is easily transported “when we move plant materials around and it has been accidentally introduced to many areas of the globe. It entered and was established in New Zealand by January 2006 based on photos sent to me in February 2006 and verified by my former graduate student Barry Donovan (PhD, UC Davis, 1969) who held up publication of his Bees of New Zealand (Donovan 2007) to include this exotic species.” 

The entire issue surfaced when the Sacramento resident wrote a letter on Jan. 10, 2011 asking that the Sacramento Municipal Utility District (SMUD) rescind its order to remove his small flower bed, which fronts a SMUD electrical transformer box in his front yard. He said he planted it 20 years ago and it is a research laboratory.

“My front yard driveway flowerbed is the only known location in the continental western United States, west of Missouri, where the European Wool Carder Bee has been found and reported to habitate,” he wrote in his open letter to SMUD officials, cc’ing UC and other scientists, state and county agricultural officials, Sacramento city officials, the Sacramento State Beekeepers' Association,  and the news media. Describing himself as a retired entomologist, he wrote that “the new species of bee which I found may provide an answer as to why our European Honey Bees are disappearing.”

Since the broadcast and other published reports, Internet users have praised his "amazing discovery," applauded the "cause" of colony collapse disorder and called for interventions. Many are contacting the UC Davis Department of Entomology for consultation or more information.

“The story is being gobbled up by the general public due to all the media hype,” Thorp said. “I just had a UPS delivery guy ask me about “this new bee that is destroying our honey bees.”

(Editor's note: See more photos of the wool carder bee by Kathy Keatley Garvey)

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--Kathy Keatley Garvey
Communications specialist
UC Davis Department of Entomology
(530) 754-6894