- Author: Kathy Keatley Garvey
If you've ever stepped in sticky gum, it's similar to what happens when an insect steps into milkweed pollinia.
Take the wasps visiting the tropical milkweed (Asclepias curassavica) on Thursday morning, July 16 in the UC Davis Arboretum and Public Garden.
They foraged on the colorful red, yellow and orange blossoms, and as nature intended (for reproductive reasons), flew off with that sticky pollinia from the anthers.
Basically, pollinia is a sticky packet of golden pollen grains originating from a single anther. The wishbone-shaped pollinia are in a nectar trough where insects often get trapped. Some insects manage to escape but leave body parts behind. A foot here...a wing there...an antenna over there...
One wasp exited a flower with "the golden glue" on its feet.
“Too funny with all the milkweed pollinia all over its feet,” commented Lynn Kimsey, director of the Bohart Museum of Entomology and Nematology and professor of entomology at UC Davis, who identified the wasp as a species of Podalonia, parasitoidal wasps in the family Sphecidae. "It looks like it's wearing fluffy socks.”
We've seen honey bees on showy milkweed (Asclepias speciosa) struggling to free themselves, only to find the bees dead the next day--and new recruits buzzing in for their share.
These Podalonia wasps, however, managed to navigate the "traps" quite well.
They'll be back for another round.
(Reminder: Folks planting the tropical milkweed in temperate zones (like here in Davis, Calif.) must remove or cut back the tropical milkweed by winter. "A protozoan parasite of monarch butterflies, Ophryocystis elektroscirrha or OE for short, can travel with monarchs visiting the plants and become deposited on leaves," explains the Xerces Society for Invertebrate Conservation.)





- Author: Kathy Keatley Garvey
So here's this tattered old worker bee seeking some nectar from the broadleaf milkweed, Asclepias speciosa. She looks as if she's not only been around the block a few times but around the county several dozen times. Her wings look too ragged to support her flight back to her colony. She'll probably live just a few more days. Worker bees live only four to six weeks in the peak season, and this is the peak season.
She bends her head and sips nectar, only to realize she is not alone. She encounters long antennae...the long antennae of a monarch caterpillar munching on a blossom. Whose plant is this? The bee wants the nectar. The monarch caterpillar wants the entire plant. This is the larval host plant of the monarch butterfly, Danaus plexippus. The caterpillars turn into veritable eating machines, devouring the leaves, flowers and some of the stems. Without milkweed, no monarchs. It's a matter of survival.
The tattered old bee touches antennae with the hungry caterpillar--Well, hello, there, dining companion!--and she backs off. There will be another blossom--if she moves quickly to claim it.
Another bee, this one much younger than the senior citizen bee, buzzes over to nearby blossom while another caterpillar, partially hidden, munches away. The bee gets stuck in the sticky mass of gold pollinia and struggles to free herself, just as another bee flies off with some of that gooey "winged" substance, anchoring her flight. She will remove it. She will return. The nectar is too enticing.
Just another chapter in the Saga of the Milkweed, the Bee and the Caterpillar...




- Author: Kathy Keatley Garvey
How times change with the advancement of knowledge.
It's long been known that when honey bees—as well as other insects—get trapped in the milkweed's pollinia, or sticky mass of pollen, many perish when they are unable to free themselves.
So when we were perusing the book, ABC of Bee Culture, published in 1890 and written by noted beekeeping innovator/entrepreneur A. I. Root (1839-1923) of Ohio--with information “gleaned from the experience of thousands of beekeepers from all over the land”--we came across a surprising recommendation.
The surprising recommendation: If you want to kill off bees where they are not wanted, plant milkweed. In one reference, milkweed is described as a “useless weed.” (Actually, it's the only larval host of the monarch butterfly and without milkweed, no monarchs.)
Excerpt from ABC of Bee Culture:
"Milkweed (Asclepias cornuti). This plant is celebrated, not for the honey it produces, although it doubtless furnishes a good supply, but for its queer, winged masses of pollen, which attach themselves to the bees's feet and cause him to become a cripple, if not to lose his life. Every fall, we have many inquiries from new subscribers in regard to this queer phenomenon. Some think it is a parasite, others a protuberance growing on the bee's foot, and others, a winged insect enemy of the bee.” (Note that foragers are referred to as male, but all foragers are female.)
“It is the same that Prof. Riley alluded to when he recommended that the milkweed be planted to kill off the bees when they become troublesome to the fruit grower. The folly of such advice—think of the labor and expense of starting a plantation of useless weeds just to entrap honey bees---becomes more apparent when we learn that it is perhaps only the old and enfeebled bees that are unable to free themselves from those appendages, and hence the milkweed can scarcely be called an enemy. The appendage, it will be observed, looks like a pair of wings, and they attach themselves to the bee by a glutinous matter which quickly hardens so it is quite difficult to remove, if not done when it is first attached.”
There's a wealth of information in the encyclopedic ABC of Bee Culture, even the 126-year-old edition, but planting milkweed to kill bees and describing milkweed a "useless weed" aren't two of them.
How times change with the advancement of knowledge.
(Editor's Note: The newest edition of the ABC of Bee Culture is The ABC and Xyz of Bee Culture: An Encyclopedia of Beekeeping, 40th Edition. It's published by the A. I. Root Co.)


- Author: Kathy Keatley Garvey
Bees--and other pollinators--gravitate toward the enticing aroma of the milkweed, too.
The milkweed is widely known as the larval host plant of the monarch butterflies--and a nectar source for the adults--but they have to share.
Bee-cause.
The broadleaf milkweed, Asclepias speciosa, in our pollinator garden draws everything from honey bees to leafcutter bees to carpenter bees.
It's almost like "Take a number." And it's especially noticeable during National Pollinator Week, a week set aside to celebrate the pollinators and to do what we can to protect them.
Recent visitors to the milkweed have included:
- A male Valley carpenter bee, Xylocopa varipuncta, a green-eyed blond
- A female Valley carpenter bee, Xylocopa varipuncta, solid black
- Honey bee, Apis mellifera
- Male leafcutter bee, Megachile sp.
And, of course, the monarchs (Danaus plexippus)!





- Author: Kathy Keatley Garvey
The honey bee struggled, but couldn't free herself from a broadleaf milkweed blossom in our pollinator garden. Had a predator nailed her? Or was the bee dying of natural causes? What was happening?
Two hours later we returned. The bee, now in a frenzy, was still stuck. We offered her sips of honey from a coated toothpick.
"Ah, with that flight fuel, she'll take off," we thought. She did not. Closer examination revealed her foot (tarsi) stuck in a mass of sticky pollen.
We separated the bee from her floral trap by lifting her from the gluelike pollinia with the toothpick. Off went the pollinia and off went the bee.
“If you hang around that milkweed, you might be able to get a photo of a bee carrying pollinia on its foot,” Extension apiculturist (emeritus) Eric Mussen of the UC Davis Department of Entomology and Nematology told us.
So, last weekend, armed with a camera and the memory of the frenzied bee, we waited. And waited. And waited. And got it. A bee flying off chained with golden pollinia.
Unlike most flowering plants, only milkweed and orchids produce pollinia, which is a sticky packet of golden pollen grains originating from a single anther. The wishbone-shaped pollinia are in a nectar trough where insects--or parts of them--often get trapped. This is a devious way for milkweed and orchids to force insects to “take me with you” and “help us reproduce.” If you're a small insect and/or not strong enough to loosen the grip, you'll be lodged in that sticky mass and die. It's sort of like jumping into quicksand and you can't get out. Some insects manage to escape but their parts remain. That's probably one reason why you see "amputated" bumble bees, carpenter bees, honey bees and butterflies, no thanks to the Sophisticated Reproductive Habits of the Milkweed (and Orchids).
The milkweed plant is not only the larval host--and only larval host--of the monarch butterflies, but it's a nectar source for butterflies and for many other insects--including honey bees, leafcutter bees, bumble bees, carpenter bees, syrphid flies and ants.
In fact, if you look closely at a broadleaf milkweed blossom (Asclepias speciosa), you'll see dozens of tiny pink flowers forming the umbel or umbrella-shaped structure. The corona, located on top of the petals, holds a circle of five hoods and five horns. Hoods and horns pointing the way. The hoods that hold that oh-so-sweet nectar beckon insects like a kid to a candy store. Each blossom has five vertical slits which house the reproductive organs.
So, what was happening? Ms. Honey Bee, seeking nectar for her colony, hit a sweet jackpot and repositioned herself to gather it. Then her foot slipped into one of the five sticky slits and she couldn't remove her leg.
Ms. Honey Bee survived, thanks to a human being with a toothpick. Others are not so lucky.




