Posts Tagged: Vespula pensylvanica
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.
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)
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)
The question begged for an answer.
"It's yellowjacket time again. Does anyone have or recommend a good trap?"
A Bay Area beekeeper today sought recommendations from ledEric Mussen, Extension apiculturist with the UC Davis Department of Entomology and Nematology.
Mussen, who recently co-authored "Yellowjackets and Other Social Pests" on the UC IPM website with Michael Rust of UC Riverside, responded candidly.
"There are a number of ways that people try to deal with populations of yellowjackets at this time of year," he told her.
- If you can find the nesting area, a whole colony can be dealt with, directly.
- If you can’t find the nest, then most people resort to trapping, since putting out poisonous baits no longer is legal. You can purchase the yellow plastic traps at hardware and nursery stores, etc. You can catch quite a substantial number of wasps, but that often does not alleviate the problem. Similar traps in the spring, to intercept the foundresses, accomplishes a lot more in the long run. These traps contain a pheromone that attracts the wasps. Put the traps a good distance away from where you hope to have a wasp-free location.
- In many outdoor areas, people will tie a piece of raw meat suspended over a tub of detergent water. The wasps come and gorge themselves, then tumble into the water and drown. Again, this does not mean that you will get them all and no longer be vexed. Also, you may have to deal with other scavengers that will eat old meat.
- If the wasps are going after your bees, this is a good time to put “robbing screens” on the entrances to your hives. They pretty much stop honey bee robbing and they are helpful with wasp problems, too, where the wasp populations are not too high. You can see my idea of a good design at my Bee Briefs on our Entomology website. See Robbing Screen.
Western Yellowjackets (Vespula pensylvanica) like to hang around or nest near apiaries because it's "one-stop shopping," as former UC Davis postdoctoral scholar Erin Wilson, now an assistant professor of entomology at UC Riverside, said at a UC Davis seminar in December 2010.
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.
Yes, it's that time again when beekeepers figuratively "see red" when they see yellow (jackets).
A yellowjacket entering its nest at an apiary. (Photo by Kathy Keatley Garvey)
A yellowjacket sipping water at an apiary. (Photo by Kathy Keatley Garvey)
As the guests dined on seafood, yellowjackets dined on bits of protein left behind.
The half-filled glasses were there to draw the yellowjackets away from the picnic tables. Don't know what was in the plastic glasses, but whatever it was, it did not kill them. It just slowed them down. A little. They jumped in, swam around, and climbed out.
Yellowjackets (genera Vespula) are pests.
"Defensive behavior increases as the season progresses and colony populations become larger while food becomes scarcer," wrote authors Eric Mussen of Uc Davis and Michael Rust of UC Riverside in the newly updated UC IPM Pest Note, Yellowjackets and Other Social Wasps.
"In fall, foraging yellowjackets are primarily scavengers, and they start to show up at picnics and barbecues, around garbage cans, at dishes of dog or cat food placed outside, and where ripe or overripe fruit are accessible. At certain times and places, the number of scavenger wasps can be quite large."
Yes, indeed. Uninvited guests are likely to join your picnic.
The ones we observed were Vespula pensylvanica, commonly referred to as "meat bees" because they like meat, including the hamburgers, hot dogs and other protein you serve at your picnic and at other outdoor outings. They also like sugary drinks.
An excerpt from the Pest Note:
"Usually stinging behavior is encountered at nesting sites, but sometimes scavenging yellowjackets will sting if someone tries to swat them away from a potential food source. When scavenging at picnics or other outdoor meals, wasps will crawl into soda cans and can sting your lips or the inside of your mouth or throat."
Want to know more about yellowjackets and other social wasps? Access or download the Pest Note.
Yellowjackets are attracted to this plastic container. (Photo by Kathy Keatley Garvey)
Close-up of yellow jackets. They soon climbed out and flew away. (Photo by Kathy Keatley Garvey)
What's that? A honey bee and a male yellowjacket on the same blossom?
Honey bees and yellowjackets belong to the same order, Hymenoptera, but different families. The honey bee (Apis mellifera) is in the Apidae family, while the yellowjacket, Vespula pensylvanica, belongs to the family, Vespidae.
When beekeepers open the hives at the adjacent Laidlaw facility, trouble can start between the honey bees and the yellowjackets. It's no secret that female yellowjackets establish their nests near apiaries to prey upon honey bees and their brood. They need the protein for their offspring.
But here they were--the honey bee and the yellowjacket--together.
The first occupant: the honey bee. She began foraging on a rose blossom when suddenly a male western yellowjacket approached her. Seemingly unaware of his presence, she kept foraging. He poked her with his antennae. She ignored him. He crawled up next to her and took a close look at her. She kept foraging.
A few seconds later, he left.
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, later commented: "I can't help but wonder why the male yellowjacket was visiting a rose flower--no nectar there, so no reward for him."
"Maybe he was just checking out the other occupant 'while searching for love in all the wrong places.' "
Indeed, the male yellowjacket may have been looking for a suitable mate.
This one? Definitely not suitable!
Male yellowjacket heads toward a honey bee. (Photo by Kathy Keatley Garvey)
Male yellowjacket checks out the honey bee. (Photo by Kathy Keatley Garvey)
Honey bee continues to forage, while the male yellowjacket crawls away. (Photo by Kathy Keatley Garvey)
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