"Sweat bees have earned their common name from the tendency, especially of the smaller species,to alight on one's skin and lap up perspiration for both its moisture and salt content."
So write University of California scientists in their award-winning book, California Bees and Blooms, a Guide for Gardeners and Naturalists.
California has some 1600 species of undomesticated or wild bees, point out the authors (Gordon Frankie, Robbin Thorp, Rollin Coville and Barbara Ertter).
And one of them is the sweat bee, Halictus ligatus, a member of the family Halictidae. It's a medium-sized, ground-nesting bee with a striped abdomen.
This week one of these species (as identified by research scientist John Ascher) looked especially striking on a Black-Eyed Susan, Rudbeckia hirta, a member of the Aster (Asteraceae) family. Both the plant and the bee are natives.
Several years ago we managed to photograph a flameskimmer dragonfly, Libellula saturata, munching on one of these sweat bees. Not a good day for that little gal!
No dragonflies were around, however, when we watched this one foraging on a Black-Eyed Susan.
Did you know that the Black-Eyed Susan is the designated state flower of Maryland? And that it was the inspiration for the University of Southern Mississippi's school colors (black and gold)? And that it's a larval host to butterflies such as the bordered batch, gorgone checkerspot and silvery checkerspot?
Who knew? If you plant it, though, be aware that it is toxic (when ingested) to cats.
Don't bring a pillow, a night-cap or an attitude—it's Boys' Night Out and we're sleeping outside on the flowers.
That's what the male longhorned bees, Melissodes agilis, do while the females return to their underground nests at night.
"It's a bee B&B," quipped Lynn Kimsey, director of the UC Davis Bohart Museum of Entomology and distinguished professor, UC Davis Department of Entomology and Nematology.
This native species is among California's 1600 species of undomesticated bees.
Ever seen a Boys' Night Out? It's fascinating. The boys curl into a comma, or doze with their heads down and striped abdomens up.
Over the last two weeks, we've been monitoring the number of males sleeping on a single Mexican sunflower, Tithonia rotundifola, in our Vacaville pollinator garden. On the first night, two. Then three, then four. The slumber party grew to five last night. They sleep on a 10-foot-high blossom (talk about height advantage and a bird's eye view)! Every night, they return to the very same blossom.
A few years ago we saw the males sleeping on our lavender stems and then they moved to Gaura stems, probably due to the proximity of three praying mantids.
Folks ask if they sting. No. Boy bees don't sting. They can't.
The late Robbin Thorp, distinguished emeritus professor of entomology and co-author of California Blooms and Bees: an Identification Guide for Gardeners and Naturalists, fielded scores of questions on these slumbering bees. “They (males) lack a stinger which is a modified ovipositor in their wasp ancestors. Boy sleeping aggregations are based on a suitable perch and not related to where females are nesting, but probably no more than 100 yards from the nearest female nest. Females nest in the ground and have rather distinctive round holes about the diameter of a pencil or slightly smaller, sometimes with small piles of dirt around them looking like mini-volcanos. The holes may be widely separated or clustered together depending on the species, but each female digs her own burrow."
Of course, not all slumbering bees in this area are Melissodes agilis, as Thorp pointed out. Some may be other species of the genus Melissodes and some may belong to the closely related Svastra obliqua.
The boy bees start arriving for their nightly sleepover around 5 p.m. or when the light fades. Sometimes they appear to be kicking each other before settling down for the night. Said Thorp: "Each establishes his own spot, so there may be some jostling for position initially."
When it's morning, they rise, warm their flight muscles, sip a little nectar, and begin dive-bombing the honey bees, carpenter bees, bumble bees, butterflies, syrphid flies and assorted other insects on "their" flowers. M. agilis are very territorial. They're trying to save the food source for the females of their own species—so they can mate with them, as Thorp related.
When their day ends, they cluster for another Boys' Night Out. It's "Nighty Night, Sleep Tight." Time to curl up on a cushion of petals beneath a blanket of stars.
"Bee B&B," as Professor Kimsey says.
It's Day 6 of National Pollinator Week.
Meet the drone fly (Eristalis tenax), often mistaken for a honey bee.
The late Robbin Thorp, UC Davis distinguished emeritus professor of entomology, used to jokingly call it "The H Bee," pointing to the "H on its abdomen.
It's not a bee, though, it's a fly. It belongs to the family Syrphidae (which includes insects commonly known as syrphids, flower flies, and hover flies) in the order, Diptera.
The drone fly about the size of a honey bee. However, unlike a honey bee, the drone fly "hovers" over a flower before landing.
Drone fly larvae are known as rattailed maggots. They feed off bacteria in drainage ditches, manure or cess pools, sewers and the like.
But just think of the adult. It's a pollinator. Just like the honey bee.
It's Day 3 of National Pollinator Week.
Fortunately, a tiger came to visit us--no, not the predatory jungle animal, Panthera tigris, but a newly emerged Western tiger swallowtail, Papilio rutulus.
This native butterfly is quite colorful, with black stripes accenting its brilliant yellow wings, and blue and orange spots gracing its tail. When it flutters into your garden, you stop everything you're doing and become a professional butterfly watcher until it leaves. It's the law, I think. Anyway, Western tiger swallowtails are almost hypnotic.
This fluttering tiger took a liking to our Mexican sunflower, Tithonia rotundifola, and was totally unaware of a tiny longhorned bee, a male Melissodes agilis, heading straight for it.
Pretend you're the butterfly. Here you are, newly emerged and you've discovered a patch of Tithonia offering delicious nectar! Heaven scent! Then you see a speedy little critter targeting you. He's not about to make a lane change. There's no garden patrol to monitor his speed or aggressive behavior. He's coming for you. He aims to hit you and dislodge you from your perch.
This little bee, in fact, targets all critters occupying "his" flowers. He isn't out to sting the floral occupants, as one reader surmised. It's a male bee, and boy bees can't sting. Nor is he fighting over pollen. Males do not collect pollen or nectar for their colony--the females do.
So what is he doing? He's trying to protect or save the floral resources for the females of the species so he can mate with them. The late Robbin Thorp, noted bee expert and distinguished emeritus professor of entomology at UC Davis, used to talk about these little guys bullying all the floral tenants--from Valley carpenter bees to majestic monarchs to praying mantids. Sometimes an unfortunate Melissodes winds up in the spiked forelegs of a mantis. Or in the clutches of a spider. Or in the beak of a bird.
It's a jungle out there. Sometimes it's the survival of the fittest. Or the flittest.
But have you ever seen the digger bees?
They're out there.
The sand cliffs are the home of the digger bee, a bumble bee mimic known as Anthophora bomboides stanfordiana. This bee builds turrets in the sand cliffs.
Last Thursday we watched several digger bees warm their flight muscles, take flight, and forage on the lupine, wild radish, and seaside daisy. Then we saw the females zipping in and out of their turrets: their cozy castles in the sand.
As the late Robbin Thorp, a global authority on bumble bees and a UC Davis distinguished emeritus professor of entomology, told us several years ago: "The species name indicates that it is a bumble bee mimic. These bees need a source of fresh water nearby. Females suck up water, regurgitate it on the sandstone bank surface, then dig away at the soft mud. They use some of the mud to build entrance turrets, presumably to help them locate their nests within the aggregation of nests."
"The female," Thorp said, "sucks up fresh water from nearby, stores it in her crop (like honey bees store nectar) for transport to the nest. She regurgitates it on the sandstone, and excavates the moistened soil. She carries out the mud and makes the entrance turret with it."
As part of a National Science Foundation grant, community ecologist Rachel Vannette, assistant professor, UC Davis Department of Entomology and Nematology, is teaming with other colleagues, including pollination ecologist Stephen Buchmann, to research these digger bees and their nests.
It's a big beautiful bee world out there.