Backyard Orchard News
They're here. They're there.
The Western yellowjacket (Vespula pensylvanica) likes to hang around bee hives.
If you're a beekeeper, you've probably seen them nesting in a rodent burrow or hollow log near your hives.
At the Harry H. Laidlaw Jr. Honey Bee Research Facility at the University of California, Davis, yellowjackets currently occupy two rodent holes a few feet from the hives. To mark the spot, beekeeper and research associate Elizabeth Frost placed a brick over each nest (see photo below).
The yellowjackets are not welcome.
Members of the Vespula genus are "the most abundant and troublesome wasps in California," according to scientists Jerry A. Powell and the late Charles L. Hogue in their book, California Insects, published by the University of California Press.
"The voracious workers attack everything in the vicinity, from resting insects to pieces of hamburgers on the picnic table," they noted, and "the colonies may become very large by late summer or fall."
Bee breeder-geneticist Susan Cobey, who divides her time between UC Davis and Washington State University, agrees that yellowjackets "can be a big problem. I've seen them kill hives."
Cobey says she's fighting them now in Island County, Washington. "I have only 10 colonies, but these are special--the imports (for bee research). The wasps are always hanging around the entrance harassing the bees."
"I've had to move hives at times because the invasion was decimating the bee population," she said. "They go for the thorax (meat). They especially like the drones being kicked out of the hives in the fall--big and juicy. This is an easy dinner so then they start going in the hives and taking workers."
One way to counter the yellowjacket invasions is to "reduce the size of the entrance so the bees can protect themselves." Also, beekeepers must "keep the hives strong and healthy--yellowjackets pick on the weak."
To decrease the yellowjacket population, beekeepers bait traps in the summer "as the reproductives come out," Cobey says.
Since yellowjackets are meat eaters and honey bees are not--you can use cat food with the bait.
"But the bait must be protected from other critters," Cobey cautions. "You can put in it an empty beehive with a very small entrance."
(Note: Postdoctoral scholar Erin Wilson of the Louie Yang lab, UC Davis Department of Entomology, will speak from 12:10 to 1 p.m., Wednesday, Dec. 1 in 122 Briggs on how yellowjackets are wreaking havoc in Hawaii. Listen live at http://uc-d.na4.acrobat.com/ucsn1/. The seminar later will be archived.)
Emerging from Hole
They probably annoy you when they invite themselves to your barbecue to partake of your hamburger and other protein-rich foods. They're persistent predators.
But, do you know that they often build their nests near bee hives? "It's one-stop shopping," says postdoctoral scholar Erin Wilson (right) of the Louie Yang lab, UC Davis Department of Entomology.
Yellowjackets prey on honey bees. They raid the hives (killing the adults and brood, and stealing honey) and take the food back to their young.
Wilson, who does research on the Western yellowjacket (Vespula pensylvanica), is the lead author of a research article published in the Nov. 11 edition of Ecology.
On Wednesday, Dec. 1, she'll discuss "Yellowjacket Life History Shifts Modify Invasion Impacts in Hawaiian Ecosystems" at a UC Davis Department of Entomology seminar, set from 12:10 to 1 p.m., in 122 Briggs Hall. The talk, open to the public, also will be webcast live at http://uc-d.na4.acrobat.com/ucsn1/ and then archived on the entomology website.
The Western yellowjacket is an introduced, invasive species in Hawaii. Native to the western United States, it was first discovered in Hawaii in 1977. It's like a "vaccuum cleaner," Wilson says, and is clearly a threat to native species in Hawaii.
“The introduction of non-native organisms is a leading cause of imperilment of native species,” says Wilson, who since 2004 has studied the social wasps at two sites: the Hawaii Volcanoes National Park on the island of Hawaii and the Haleakala National Park on Maui.
The yellowjacket “may seriously threaten endemic invertebrates that evolved in the absence of these social insects," she says. "Invasive predators affect native species directly and indirectly, and the magnitude of these effects is highly dependent on the history of the recipient community. Furthermore, the impact of this social wasp may be magnified by apparent shifts in colony structure in the introduced range."
Scientists have found that the incidence of perennial or overwintering colonies is higher in Hawaii than in the native range of V. pensylvanica.
Compared to annual colonies, overwintering perennial colonies can collect twice as many prey items and produce 10 times the worker force, Wilson says. Some perennial colonies were huge, the size linked to Hawaii’s mild climate and the ability of the yellowjackets to establish perennial colonies. One Maui colony included as many as 600,000 individuals.
Yes, that's 600,000 wasps! In its native range, the typical size is less than a few thousand wasps.
Check out Wilson's research article, yellowjacket photos and her website and then listen to her seminar on Dec. 1:
- Multiple Mechanisms Underlie Displacement of Solitary Hawaiian Hymenoptera by an Invasive Social Wasp (E. E. Wilson and D. A. Holway, Ecology journal)
- Photos from her research and UC San Diego news story
- Erin Wilson's website, Vespularesearch.com
President Obama just pardoned a couple of turkeys--Apple and Cider. They won't make it to the White House Thanksgiving dinner today.
But what he could have done--when he was pardoning the turkeys--was to praise the honey bees.
Without honey bees, Thanksgiving Day dinner--as we know it--would not exist.
It's time to "bee" thankful.
If your table includes pumpkin, cranberries, carrots, cucumbers, onions, apples, oranges, cherries, blueberries, grapefruit, persimmons, pomegranates, pears, sunflower seeds, and almonds, thank the bees for their pollination services.
Spices? Thank the bees, too. Bees visit the plants that eventually comprise our spices, including sage, basil, oregano and thyme.
Extension apiculturist Eric Mussen of the UC Davis Department of Entomology faculty, says that even milk and ice cream are linked closely to the honey bee. Cows feed on alfalfa, which is pollinated by honey bees (along with other bees).
So, pardon the turkeys? Well, at least "Apple" and "Cider." But let's praise the honey bees, too.
Bee on Pomegranate Blossom
Mark your calendar.
If you're a bee aficionada and haven't ordered your educational North American Bee Calendar, you have until Tuesday, Nov. 30 to place your order.
It's for a good cause. Proceeds benefit the pollination services work by the Xerces Society for Invertebrate Conservation and the Great Sunflower Project.
This is an order-online-only calendar, says Celeste Ets-Hokin, the Bay Area native bee enthusiast who is spearheading the second annual project. That means you won't find the calendar in any stores and you won't be able to order it after Nov. 30.
The calendar spotlights a different bee genus each month, with notes on preferred plants, nesting needs, and guidance on how to identify the genus. In other words, it's a good way to learn about bees: what they look like, where they live and how to entice them to your garden.
At the UC Davis Department of Entomology, we frequently get requests for information on bees. "What are those big black bees buzzing around my garden?" they ask. "What does a leafcutter bee look like? How can I attract bumble bees?"
If you're around entomologists, you'll hear them talking about Osmias, Lasioglossums, Xylocopas and Agapostemons.
Bees appearing in the calendar and the scientific names are:
January: Honey Bee (Apis)
February: Bumble Bee (Bombus)
March: Digger Bee (Habropoda)
April: Mason Bee (Osmia)
May: Sweat Bee (Lasioglossum)
June: Ultra Green Sweat Bee (Agapostemon)
July: Leafcutter Bee (Megachile)
August: Squash Bee (Peponapis)
September: Long-horned Bee (Melissodes)
October: Carder Bee (Anthidium)
November: Carpenter Bee (Xylocopa)
December: Cuckoo Bee (Epeolus)
The photos by Rollin Coville of Berkeley are stunning. The green metallic sweat bee glitters like emeralds.
Calendars are $15 each, which includes shipping anywhere in the United States. The international price is $18, shipping included. Orders may be placed by accessing the Xerces website or The Great Sunflower Project website.
Coville, who has a doctorate in enotomology from UC Berkeley, collaborates with Gordon Frankie of UC Berkeley and emeritus professor Robbin Thorp of UC Davis on urban bees.
Indeed, the calendar is the work of many scientists and "bee folks." Matthew Shepherd, senior conservation associate of the Xerces Society, and Ets-Hokin served as editors, and Miguel Barbosa as the graphic designer. Scientists sharing their research expertise included: Neal Williams of UC Davis; Gordon Frankie and Claire Kremen of UC Berkeley; and Rachael Winfree of Rutgers University, New Brunswick, N.J.
North American Bee Calendar
Recently single adult psyllids were found on two traps about 1 mile apart from each other in Upland California (San Bernadino County). The host plants in and around these traps are being treated and these finds will expand the quarantine zone (20 miles around a psyllid find). The populations in Imperial, San Diego, and Los Angeles counties countinue to have the occasional new psyllid finds, but the area that is being treated has not expanded very much. This is evidence that the insecticide treatments are very effective - if we can find this tiny insect! We continue to get the good news that no huanglongbing disease has been found in California.