They Came for Sex Among the Redwoods

The brightly-colored beetles mate by the gazillions in winter, and Redwood Regional Park where the Prince and Stream trails meet is a particularly lusty lair.


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Ladybug love in the redwoods is an annual occurrence in the East Bay.

Photo by Brad Polt-Jones

Winter brings its annual pastimes: The snap and crackle of the fireplace, the brisk wintery chill of the slopes … and the odd, toxic odors of ladybugs having sex.

Each December, gazillions (no one can count just how many) ladybugs swoop in to blanket parts of the East Bay and beyond, to places like the Huckleberry Botanic Regional Preserve, Joaquin Miller Park, and Redwood Regional Park. Redwood perhaps is the most notable of the ladybug hangouts, because of how accessible the trails are to mainstream hikers. Specifically, the ladybugs love to converge at Steam Trail where it meets Prince Trail.

The ladybugs are probably clustering in other spots, too, but “we just don’t know where they are,” said East Bay Regional Park District naturalist Michael Charnofsky, who has been studying the brightly colored beetles for the last five years.

A lot is still unknown about the popular insects. Don’t call them bugs; they’re arthropods in the beetle family. Getting a GPS tracker attached to one of their tiny legs ain’t so easy.

But many ladybug enthusiasts and serious entomologists have been sharing information though the Lost Ladybug project, started at Cornell University in 2000 in an effort to document the elusive species. The project went digital in 2004 so that “citizen scientists” can upload ladybug sightings around the globe to try to better understand where ladybugs live and what they do.

What Charnofsky and other naturalists have been able to surmise is that ladybugs are flying in from somewhere out west and are seeking cold, moist temperatures so that they can mate during the warm, winter afternoons. Since you asked, here’s the primer on ladybug sex: Ladybugs excrete scents to find each other. When they do, the male grips the female from behind and holds on tightly. They can copulate for more than two hours at a time. Female ladybugs can store a male’s sperm for several months before laying eggs.

The ladybugs love the relative moisture of the redwoods and are likely sniffing out “pheromones from the past” to keep returning to the same spots, Charofsky said. The ladybugs usually start coming in mid-November and in much larger concentrations in December, he said. Serious ladybug mating occurs in February when the sun is higher and the days are longer, before the insects take off. They usually vanish from Oakland by March, he said.

“Where do they go?” Charnofsky asked. “We don’t know exactly. That’s exciting. Trying to find proof.”

What Charnofsky definitely has proof of is that ladybugs give off a distinctive odor that smells, well, very much like “ladybug.” They excrete a “nasty chemical, acidy smell” if threatened, Charnofsky said. “And they’re somewhat toxic to eat.”

In the last year or two, the ladybug droves have seemed a bit smaller, he noted, likely because of the drought yielding fewer insects in general and thus attracting fewer aphid-eating ladybugs. And so, since California’s soil and forests have been drier, Charnofsky estimates that the population of ladybugs that he’s witnessed seems to be only in the tens of thousands instead of the millions.

Still, any size ladybug cluster is OK with Ollie Krause, 12, of Berkeley, one of the many visitors who hike the park just to see the orange-y bugs. The Convergent Ladybug, the kind spotted at Redwood Regional, is typically a dull orange in the winter.

“We go a few times a year just to see the ladybugs,” he said. “They’re just a massive, swarming body of insects, and it’s so cool.”

That “cool” is usually what brings folks out to the park in the winter to witness a multitude of insects that are pretty much beloved, at least much more so than the average mosquito, cockroach, or spider. “Kids want to hold and touch them,” Charnofsky said. “It’s just an amazing thing. It’s not something we’re used to.”

If you’re interested, Redwood Regional Park is offering a Redwood, Ladybug, Ladybug, Where Do You Go? Walk from 10 a.m. to noon on Dec. 13.

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