The late Argentine-born biologist Beatriz Moisset (1934-2022) of Willow Grove, Pa., called the insect "A Pollinator with a Bad Reputation."
Moisset, who received her doctorate from the University of Cordoba, Argentina, and authored the book, Bee Basics, an Introduction to Our Native Bees, was referring to bee flies, from the family Bombyliidae. In their larval stage, these flies parasitize the eggs and larvae of ground-nesting bees, beetles, and wasps.
They superficially resemble bees. If you look closely, however, they have one-pair of wings (bees have two pairs), and their antennae are short and stubby, unlike that of bees.
They neither bite nor sting. Bombyliidae includes some 4500 described species, found throughout North America, Europe and Asia, with many more undescribed.
If you see these long-legged, fuzzy-looking insects, they're usually foraging on flowers or hovering above the ground.
"The reason why it diligently hovers over bare ground early in the spring is that it is looking for bee nests," Moisset wrote in a piece published on the U.S. Forest Service website. "The bees dig tunnels and lay their eggs at their bottoms after collecting enough pollen to feed the larvae. This requires numerous trips, thus the bee fly takes advantage of the mother's absence and lays its eggs in such nests. Making use of its flying prowess, it does not even need to land but it flicks its abdomen while hovering over the open burrow, letting one egg fall in or near it."
"The fly larva finds its way to the chamber where the mother bee has laid the provisions and the egg and proceeds to feed on the stored pollen," Moisset explained. "Afterwards it devours the bee larvae; when it is fully grown, it pupates and stays inside the nest until next spring."
We spotted a bee fly in a Vacaville pollinator on Sept. 19. It zoomed over a yellow zinnia, hovered, and then dropped down to sip some nectar. Meanwhile, looking like a cross between a bee and a fly, it skirted syrphid flies and honey bees also intent on getting their share of nectar.
The bee fly is aptly named.
Honey bees and native bees love capeweed, Arctotheca calendula, also called South African capeweed, cape dandelion and cape marigold or cape gold.
It's an invasive plant originating from the Cape Province in South Africa (Here's what the California Invasive Council says about it:
"Capeweed (Arctotheca calendula) is an annual or perennial evergreen herb that, when young, forms a low-growing rosette of heavily pinnately lobed leaves, with undersides covered by woolly down. With age, it forms an extensive, dense, mat-like groundcover by proliferation of rooting stems (stolons) from rosettes. Leaves are pinnately lobed; fine, dense hairs cause stems and leaves to appear silvery. Flowers are approximately two inches in diameter, lemon yellow, and daisy-like with yellow centers. The plant is conspicuous in late spring and early summer due to its increase in size and the profusion of large yellow daisies. Plants are seldom solitary, and they spread vigorously by creeping stems (Lasca Leaves 1968)."
Capeweed may have arrived in California in a shipment of grass seed from Australia, where it is a common weed, according to the California Department of Food and Agriculture. The invasive species compendium (CABI) listed it as a noxious weed in 2010 in California.
However, it's cultivated as an ornamental ground cover and has both "fertile" and "sterile" forms.
We've seen lawnmowers run over the the weed in City of Benicia parks (yes, it grows back), we've seen it thriving in a gold carpet along coastal California, and we've seen bees foraging on it.
It's a pollinator paradise, of sorts, but it's also invasive.
The boys are back in town.
After the long winter and rainy spring, the boys are back in town.
That would be the male Valley carpenter bees, Xylocopa varipuncta, or what Robbin Thorp, distinguished emeritus professor of entomology at UC Davis, calls "the teddy bear bees."
They're fuzzy green-eyed blonds, while the female of the species is a solid black, a good example of sexual dimorphism.
You've heard folks say of dogs: "Their bark is worse than their bite?" Well, these bees can't sting ("boy bees don't sting"), but they're good bluffers as they buzz around you. They're also good pollinators.
We saw this one nectaring on our tower of jewels, Echium wildpretii. He lingered among the honey bees and syrphid flies, and then buzzed off.
He will return.
Seeking more information about California's bees? Read the landmark book, California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday Press), the work of UC-affiliated authors Gordon Frankie, Robbin Thorp, Rollin E. Coville, and Barbara Ertte. The book is available online and at numerous other sites. At UC Davis, you can find it at the Bohart Museum of Entomology, 1124 Academic Surge Building on Crocker Lane (and with other bee books at UC Davis Stores)./span>
When a house is a home...
Take the case of a syrphid fly, aka hover fly or flower fly. It's a cold and windy day, and it's tucked in the folds of a rock purslane, Calandrinia grandiflora, in Vacaville, Calif.
It's sipping nectar, and rotating its colorful little body to gather more nectar and glean more sun.
The syrphid fly is often mistaken for a honey bee. Both are pollinators.
Three of the easiest ways to differentiate a fly from a bee:
- A fly has one set of wings. A bee has two sets.
- A fly has short, stubby antennae. A honey bee doesn't.
- A fly has no corbicula or pollen basket. A honey bee (worker bee) does.
Last year Joanna Klein posted an interactive feature in the New York Times, wondering how we can save the bees if we don't recognize them. She asked "Can You Pick the Bees Out of This Insect Lineup?" and posted an image of bees and wanna-be bees.
Find the flies.
And then access a PDF on flower flies on the UC Agriculture and Natural Resources website to learn more about them. Authored by lead author/entomologist Robert Bugg, it's titled "Flower Flies (Syrphidae) and Other Biological Control Agents for Aphids in Vegetable Crops."/span>
You may have noticed this little floral visitor in your garden.
It might appear to be a bee, a common mistake to the untrained eye or those who think that all floral visitors are bees.
But it's a fly, and flies are pollinators, too!
This fly, from the genus Eristalis, family Syrphidae (hover flies), order Diptera, is probably Eristalis stipator, says fly expert Martin Hauser, senior insect biosystematist with the Plant Pest Diagnostics Branch, California Department of Food and Agriculture.
In its larval form, Eristalis, found in aquatic habitats, is known as a rat-tailed maggot, due to its appendage that resembles a snorkel.
Next time you see this little fly on a flower, you can tell your friends "In its larval stage, it's a rat-tailed maggot."
As they widen their eyes and raise their eyebrows, you can add: "But in its adult stage, it's a pollinator."