Posts Tagged: yellowjacket
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)
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.
Faster than a speeding bullet...
As soon as UC Davis bee breeder-geneticist Susan Cobey opened a beehive and removed a chunk of honeycomb to show visitors, here came the speeding bullet. A fast camera shutter caught what the eye couldn't see.
It was a queen yellowjacket taking dead aim at the comb.
"The yellowjacket queen this time of year zeroes in on the honey as soon as you open a hive," said Cobey, manager of the Harry H. Laidlaw Jr. Honey Bee Research Facility.
"They build up their populations in the fall and eat the bees for protein to overwinter. They can actually kill bee colonies, especially weak ones. As meat-eating predators, these are common at picnic time, for which honey bees are often unfairly blamed."
Yes, honey bees are indeed unfairly blamed. Like human vegetarians, honey bees don't eat meat. They may land on your soda can for the sugar water, but meat doesn't interest them. They forage for nectar and pollen.
Now yellowjackets--they're predators. They love meats and sweets. You'll see these uninvited guests at your picnic or barbecue, boldly sampling your steak, hamburger or chicken; targeting your can of soda; or scavenging in and around your garbage can.
They also vigorously defend their nests, which look like paper combs. Do not go near their nests.
Their sting is painful. A yellowjacket recently nailed UC Cooperative Extension Apiculturist Eric Mussen beneath the collar as he was checking the honey bees at the Laidlaw facility.
Mussen noted that beekeepers inadvertently kill a few bees each time they open a hive and pry open the "stuck-together" frames with their hive tool. The dead bees fall to the ground--to the waiting yellowjackets. The yellowjackets then carry the bees off to their nest, chew them into pulp, and feed the "protein" to their brood.
More yellowjackets on the way.
And soon, more speeding bullets.