Wasp in Bay Area: Get away as fast as you can

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https://www.sfgate.com/local/article/wa ... 801461.php

A popular Bay Area park is warning visitors to take caution after reporting a “higher-than-normal population” of wasps swarming the area.

Samuel P. Taylor State Park, a 2,800-acre state park in Marin County, is home to one of the first recreational campgrounds in California and is also frequently sought out for its scenic hikes and picnic areas shaded by redwood trees along Lagunitas Creek. But over the past week, park staff have received multiple reports from visitors who have spotted the six-legged species, and staff are taking steps to track their whereabouts, Peter Ostroskie, a spokesperson for California State Parks’ Bay Area district, told SFGATE

A perfect storm of mild weather conditions over the summer and increased food availability have likely contributed to the surge in yellowjackets, a type of social wasp that is among the most common found in Northern California and loves to scavenge for its meals. Lagunitas Creek provides a constant flow of water to the park, while cooler temperatures and drizzle have not only contributed to the growth of vegetation in the area, but also the number of campers who may leave behind snacks and sweet beverages for the wasps to go after, Ostroskie said.

“Typically we see a few nests a year,” he said in an email. “This year, we have at least recorded over 10 nests that we know about.” Most of them have been marked in the day use area of the park near the creek, he added, and visitors should look out for places staff have cordoned off with cones and caution tape.

“We have not had any reports of being stung at this time,” Ostroskie said.

California State Parks officials haven’t noticed an increase in wasps at other parks to the same extent that they’re seeing at Samuel P. Taylor State Park, he said. But Lynn Kimsey, professor emerita at UC Davis and the former director of the Bohart Museum of Entomology, told SGATE that climate change may be allowing the insects to thrive over time.

Kimsey noted that wasps have trouble flying in temperatures below 60 degrees and above 100 degrees. That said, the milder winters become, the better their ability is to survive and forage, contributing to colonies that can continue year-round and grow “quite large,” she said.
“If it gets warmer and warmer like it appears, we’re going to be dealing with these guys on an ongoing basis,” she said. “They thrive in suburban settings. Open garbage dumpsters. It’s like hog heaven for them.”

Typically, wasps form new colonies on an annual basis, producing a new batch of queens and males in the fall months. They mate, the males die, and the queens go to find a space to hide out until the spring — they tend to prefer rodent burrows and other underground cavities.
But if colonies “go perennial,” meaning they don’t die during the winter due to favorable environmental conditions, they can become “enormous,” Kimsey said. “I have heard about this happening along the coast.”

Colonies of yellowjackets normally include 50,000 to 100,000 workers, but Kimsey noted one of her colleagues in Hawaii recently found a perennial nest that had an estimated 3 million wasps.

It remains to be seen if colonies will grow that large in the Bay Area. But like Ostroskie, Kimsey said people should be careful while spending time in outdoor areas like Samuel P. Taylor State Park, where the wasps seem to have found a reliable food source they’ll stop at nothing to get. She’s seen wasps fly directly into soda cans, drawn to the sweetness, only to later sting an unsuspecting person in the mouth.
“It’s one of those things nightmares are made of,” she said. “They’re grumpy, very aggressive predators.”

In some ways, that’s a benefit — they help control other insect populations that can be harmful to crops. But people who don’t want to get in their way can take a few steps to stay safe. Yellowjackets may be easy to spot due to their distinctive coloring, but their nests are less discernible and should be avoided, Kimsey said. If you do get stung, “you want to get away as fast as you can,” she said. “Unlike honeybees, they can sting you repeatedly.” If you experience swelling, trouble breathing, or other signs of an allergic reaction, go to an emergency room as soon as possible.

Ostroskie said California State Parks staff and the Marin/Sonoma Mosquito and Vector Control District are also urging visitors to avoid walking around barefoot, and make sure all of their food is covered and that the tops of their beverages are sealed. Do not swat at wasps or disturb their nests — and if you spot one, report it to a ranger or a visitor kiosk.

“We are also working with local vector control to have technicians come out as often as they can,” he said.