Boys' Night Out!

Have you ever seen a cluster of longhorned male bees sleeping overnight on a Mexican sunflower (Tithonia)?

Every day around sunset, the longhorned bees, probably Melissodes agilis  (tribe Eucerini), call it a day and head for their favorite flower (bedroom), which happens to be Tithonia in our pollinator garden in Vacaville. If you grow flowers for the native bees, and you wake up early in the morning before they do, you may see them, too.

The late native pollinator specialist Robbin Thorp (1933-2019), distinguished emeritus professor at the University of California, Davis, used to call this behavior "Boys' Night Out."

"Most frequently, the boy bee overnight clusters are single-species clusters," said Thorp, co-author of California Bees and Blooms, a Guide for Gardeners and Naturalists, with UC-affiliated authors Gordon Frankie, Rollin E. Coville, and Barbara Ertter. He previously identified some of ours as Melissodes agilis.

In a previous Bug Squad blog, Thorp responded to a reader's inquiry about "stings" from the clustering bees. "Boy bees cannot sting," he pointed out. "They lack a stinger which is a modified ovipositor in their wasp ancestors.  Occasionally a girl bee may spend the night out if she is caught by sudden drop in temperature.  Usually she will not be part of a group sleep over.  So don't attempt to handle unless you are confident you can tell boy bees from girl bees or they are too sleepy to defend themselves."

The reader also asked: "Typically how close to the girls' nest(s) do the boys' slumber? I want to try and make sure I don't touch it when planting at end of summer."

 "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," Thorp answered.  "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."

The reader also wondered: "When watching the boys tonight, about ten of them started waking up and kicking each other. They finally settled down and started to nestle back in for the 'night'--it was only 6 p.m.--but I wasn't sure if my presence was getting them riled or they tend to act like kids sharing a bed?"

Said Thorp: "The boys usually settle in as the light dims in the evening.  Cool, and drizzly conditions may modify bed time. Each establishes his own spot, so there may be some jostling for position initially."

Longhorned bees are among the more than 1600 species of undomesticated bees that reside in California. The co-authors of California Bees and Blooms focus on 22 of the most common genera and the flowers they frequent.  

One of Buck Owens' signature songs that never failed to please his fan base was "I Got a Tiger by the Tail."

The Country-Hall-of-Fame singer, who died in 2006 at age 76, said the lyrics came to him after he noticed a gas station sign advertising "Put a tiger in your tank." (Source: Wikipedia)

"I've got a tiger by the tail, it's plain to see," sang Buck Owens. "I won't be much when you get through with me..."

Well, he's not the only one with a "tiger by the tail."

We recently spotted male longhorn bees, probably Melissodes agilis, targeting Western tiger swallowtails, Papilio rutulus,  in our family's pollinator garden in Vacaville, Calif. The butterflies were trying to sip nectar from the 8 to 10-foot-high Mexican sunflowers (genus Tithonia).

Who knew that sipping nectar could be so difficult? The extremely territorial male longhorn bees kept trying to push the "tigers" off the Tithonia by dive-bombing them, slamming into them, and then regrouping for more aerial assaults. Their goal: to save the resources for their own species.

And then it happened. A longhorn bee slid through a tiger's tail. 

A tiger by the tail.

Everybody eats in the pollinator garden. Everybody.

The pollinators in our garden in Vacaville, Calif., sip the nectar. They include honey bees, bumble bees, carpenter bees, sweat bees,  European wool carder bees, hover flies and assorted butterflies.

The predators eat, too.

It works like this: the pollinators eat the nectar; the predators eat the pollinators. Nature's way.

Today we watched a well-fed praying mantis, Stagmomantis limbata (as identified by Andrew Pfeifer)--look, ma, there's a "mom" in Stagmomantis--lurking beneath the leaf of a showy milkweed, Asclepias speciosa. She was apparently waiting to snag a monarch butterfly, but agreeable to a menu change. So camouflaged was Ms. Mantis that she appeared to be an extension of the leaf. There she clung, motionless but oh-so-alert.

A monarch fluttered by, landing out of reach.  Not so for the longhorn bees nectaring on the nearby African blue basil.

A longhorn bee, probably a Melissodes agilis, just wasn't quick enough to escape the Usain Bolt-like swiftness and the grasp of the spiked forelegs.

Ms. Mantis polished off the bee.

After her meal, Ms. Mantis climbed higher on the milkweed, slipping beneath another leaf to look for signs of "meal movement" below.

Well, at least she didn't nail that monarch. Not today.

It was not a good way to welcome an admiral.

The Red Admiral butterfly, that is.

The Vanessa atalanta fluttered into our pollinator garden on Sunday, July 16 in Vacaville, Calif., and touched down on a Mexican sunflower (Tithonia).

The warmth of the sun, the rich nectar, a soft breeze, and all was well.

For a little while.

Several territorial male long-horned bees spied the stranger and pulled out the welcome mat. In a frenzy, they began dive-bombing the colorful black and red butterfly, trying to chase it away. "Those flowers are for our girls!" they seemed to say. "Leave! Now!"

Everywhere the butterfly went, a squadron of bombers followed. The sailboat-like wings proved a clear target. 

One bullet-of-a-bee, probably a Melissodes agilis, slammed into the butterfly's wings, and that was enough.

"This pollinator garden's not big enough for both of us!"