If you're walking along the cliffs of Bodega Head, Sonoma County, you may overlook them.
While you're watching for whales, scouting for seabirds and checking out the hikers, there's a lot of movement in the seaside daises (Erigeron glaucus) and seaside woolly sunflower (Eriophyllum staechadifolium).
Green-eyed bullets with spectacular abdominal stripes zero in on the flowers, grab some food (this really is "fast food") and then take off at break-neck speed.
They're sand wasps, Bembix americana, so named because they dig nest holes in the sand. They belong to the family Crabronidae, subfamily Bembicinae, tribe Bembicini (sand wasps), subtribe Bembicina, and genus Bembix. They're quite common in North America. We've seen them from Fort Bragg to Bodega.
They're not vegetarians, like our honey bees. Like all wasps, they're carnivores. They're hunters. They're predators. They prey upon small insects, such as flies. The sand wasps then carry their prey back to their nests.
So while you're watching for whales, watch the flowers. If they move, it may be more than just the wind.
Want to read more about sand wasps? Entomologist Richard Bohart (for whom the Bohart Museum of Entomology at UC Davis, is named), and his former graduate student, Arnold Menke, wrote about them in their book, "Sphecid Wasps of the World," published in 1976 by the University of California Press, Berkeley.
If you're planning to hike the hills around Bodega Head in Sonoma County, watch out for the bears.
The woolly bear caterpillars, that is.
Last Sunday, with the temperature hovering around 70 degrees, the woolly bears were everywhere. They were munching on the gray-green leaves of Lupinus arboreus (yellow bush lupine), not yet blooming. We also spotted them on yellow mustard and wild radish, both members of the Brassicaceae family and both abloom.
If you look closely at these little caterpillars, they seem to be having a bad hair day. They look as if they just encountered a jolt of static electricity.
They're also known as the larvae of Ranchman's Tiger Moth (Platyprepia virginalis). Once they become moths, they do not resemble woolly bears any more.
Rick Karban, professor of entomology at UC Davis, has published a number of research papers on these herbivores.
"Platyprepia virginalis caterpillars are dietary generalists and feed on multiple host species within a single day," he wrote recently in Ecological Entomology. "We conducted field experiments to evaluate their performance on diets consisting of only their primary food, Lupinus arboreus, or diets consisting of L. arboreus plus other acceptable host species."
"We found that relative growth rates and rates of survival were higher when they fed on mixed diets compared to lupine only."
That feeding behavior we saw, too. A lupine lunch, with a touch of mustard and radish.
If you enjoy climbing the cliffs of Bodega Head on the Sonoma coast, keep your eyes out for bears--woolly bear caterpillars, that is.
The so-called "woolly bear caterpillar" is reddish, black and woolly and has a voracious appetite much like that of Joey Chestnut. It is the Ranchman's Tiger Moth caterpillar, Platyprepia virginalis.
Richard "Rick" Karban, professor of entomology at the University of California, Davis, studies this critter. "It has a taste for most alkaloid containing plants, like fiddleneck, although it doesn't appear to sequester the alkaloids," he told us. "The alkaloids may help caterpillars survive their parasitoids, however."
The reserve, which surrounds the Bodega Marine Laboratory, is a unit of the University of California Natural Reserve System and is administered by UC Davis.
Several woolly bear caterpillars were munching on fiddleneck. Another rolled around near a patch of California poppies and we couldn't tell what its menu included. It looked good, though!
You can read Karban's research on "Diet Mixing Enhances the Performance of a Generalist Caterpillar, Platyprepia virginalis," published last February in the Ecological Entomology journal.
They're populating the sandy cliffs of Bodega Head, Sonoma County. A sure sign of their presence: dense clusters of turrets.
When they're not foraging among the wild radish (genus Raphanus), lupine (genus Lupinus) and other plants, these ground-dwelling bees are digging nests and rearing their young.
"The female sucks up fresh water from nearby, stores it in her crop--like honey bees store nectar--for transport to the nest," said native pollinator specialist Robbin Thorp, emeritus professor of entomology at the University of California, Davis.
"She regurgitates it on the sandstone, and excavates the moistened soil," he said. "She carries out the mud and makes the entrance turret with it."
The digger bees are sometimes referred to as "alternative pollinators," but they're all members of the Apidae family, which includes honey bees (the super pollinators), bumble bees, carpenter bees, sunflower bees, orchid bees, cuckoo bees and the like.