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)
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
You want to make sure that Mr. and Mrs. Yellowjacket and all their offspring--plus nephews, nieces, uncles, aunts, cousins and assorted other relatives--aren't on the invite list.
And if you're a beekeeper, you don't want them killing your honey bees. "They pull the bees off at the entrance, dismember them and fly away with the parts--generally the head--to feed to their larvae," said Extension apiculturist Eric Mussen (right) of the UC Davis Department of Entomology.
Indeed, these predatory insects can be a major problem this time of the year.
When Mussen addressed the Santa Clara County Beekeeping Guild on Monday, Oct. 4, he asked the 60 attendees: "How many of you have had significant problems with yellowjackets?"
About eight hands shot up.
What to do?
"It was around a decade ago that we lost the use of flowable microencapsulated diazinon (Knox Out 2FM^® ) as a yellowjacket bait poison," Mussen said in a message he also shared today with the UC Davis Department of Entomology. "As long as the wasps did not taste it, they would take the contaminated bait back to the nests and share it with their brood and other adults. It was amazing! Often in 48 hours the colonies were out of business and the area was clear of yellowjackets."
Recently, a new microencapsulated product, Onslaught^® , containing esfenvalerate, has come on the market to be mixed into yellowjacket baits, Mussen said. Formulating the bait is the same as it was with diazinon--about 1/4 teaspoonful of the insecticide in about 12 ounces of the bait.
Yellowjackets are attracted to many odorous potential foods when their prey runs out and they turn to scavenging, said Mussen, adding that the chemical seems quite a draw when it's mixed with canned, fish-based cat food.
"Try a couple samples of cat food without insecticide to see which product is most attractive to your local yellowjacket population. Then place about three ounces of formulated bait in each trap and things should get better fast."
"You can find this product on the web as Alpine Yellowjacket Bait Station Kit. A multi-year supply (one pint) of microencapsulated esfenvalerate and four bait stations--they look like over-sized, plastic prescription bottles with a hole in the side and a string for hanging--will cost about $85 before shipping. Sounds like a lot of money for a small amount of product, but if you need to clear out the yellowjackets in a hurry--wedding reception, fair, outdoor barbecue, your own peace of mind-- this is a good investment."
And don't even think about inserting insecticidal wasp baits in that empty soda bottle lying on the ground near your picnic table. It's illegal to put pesticides, including insecticidal wasp baits, into used food and drink containers.
"The last thing you would want is for someone to accidentally eat or drink your poisoned bait," he said.