The conversation usually starts like this:
"I saw this huge, huge bumble bee with yellow on its back. It was buzzing like crazy."
Often it's not a bumble bee, but the Valley carpenter bee, Xylocopa varipuncta, that's been foraging on the blooms of the passionflower vine (Passiflora).
The yellow "markings?" Tiny yellow grains of pollen.
Valley carpenter bees are passionate about the passionflower vine, a robust climbing vine that's the host plant of the Gulf Fritillary butterfly (Agraulis vanillae).
The Valley carpenter bees are large (about the size of a queen bumble bee). The females are solid black, while the males are golden/buff-colored with green eyes. If you're lucky, you'll see both on your passionflower vine.
Planting Passiflora will usually result in a diversity of visiting species, from butterflies to honey bees to carpenter bees. You'll see Gulf Frits laying their eggs on the leaves and tendrils.
Yes, the vine will cover your fence, but not for long. The Gulf Frit caterpillars will skeletonize the plant. (And that's why we plant ours--for the Gulf Frits.)
Well, also for the other insects, too!
They didn't get the memo.
Summer is over. Fall is underway. Winter is coming (Dec. 21).
But the Gulf Fritillaries (Agraulis vanillae) are still laying eggs on the passionflower vine here in Vacaville, Calif. The eggs are hatching. The caterpillars are eating. The 'cats are pupating. And the adults are eclosing from the chrysalids.
And then the cycle of life begins all over again: from egg to caterpillar to chrysalis to adult.
Actually, we've seen Gulf Frits here year around--even photographed them laying eggs on Christmas Day. Gulf Frits don't go through diapause here. They mate year around.
Of course, the survival rate is low. An estimated 95 percent of all butterflies don't make it from egg to adult, scientists say.
We've seen why. Spiders, praying mantids, yellowjackets, European paper wasps, birds, diseases, and such parasitoids as tachinid flies and wasps that lay their eggs in the caterpillars or bore into the chrysalids.
If you look closely, you can sometimes see the parasitoid evidence (hole), such as the one below. Art Shapiro, distinguished professor of evolution and ecology and an expert on butterflies, says that judging by the size of this hole, it was a large parasitoid--probably a big tachinid fly or an ichneumonid (wasp).
Just part of the cycle of life...
Extra, extra, read all about it!
This "extra" has nothing to do with a special edition of a newspaper.
This "extra" deals with something that may puzzle you.
This "extra" refers to the passionflower vine (Passiflora), the host plant of the Gulf Fritillary butterfly (Agraulis vanillae).
About this time of year, the Gulf Frit caterpillars have probably skeletonized your passionflower vine. It's the Halloween poster child of the plant world.
But why, then, are honey bees foraging on a flowerless Passiflora? Their activity has nothing to do with pollination. They're foraging on the leaves and stems. And they're not seeking water.
Extension apiculturist (emeritus) Eric Mussen, UC Davis Department of Entomology and Nematology, answered that question with three little words: "Extra-floral nectary."
It's a subject unfamiliar to many non-botanists and non-biologists.
Wikipedia describes it this way: "Nectar is a sugar-rich liquid produced by plants in glands called nectaries, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, which in turn provide antiherbivore protection."
Lenore Durkee of Grinnell (Iowa) College wrote a scientific paper, "The Floral and Extra-Floral Nectaries of Passiflora," published in the October 1982 edition of the American Journal of Botany, that answers the question and explains the phenomenon.
She defined extra-floral nectaries as "glands that secrete primarily sugars and are found on the vegetative portions of many species of plants."
In her research, Durkee studied the extra-floral nectaries of nine species of Passiflora with light and electron microscopy prior to and during secretion. In her abstract, meant for botanists, she wrote: "There is no evidence of ER or Golfi participation in the secretion of nectar. The vascular tissue supplying the nectary is characterized by companion and pholem parenchyma cells which are usually larger than the sieve elements, a configuration similar to that found in leaf minor veins. In the petiolar nectaries, large masses of membrane-bound protein are commonly found in these cells. This protein is absent in laminar nectaries."
That's probably TMI (too much information) unless you're a botanist.
No worries. The bonus is this: the next time someone asks you why honey bees are foraging on the leaves and stems of your Passiflora (don't you hear that all the time?), you can answer "Extra Flora Nectaries" or "EFN." You can explain that flowers produce nectar but extra-floral nectaries are just nectar-producing glands physically apart from the flower. And, you could add that EFN occurs in more than 2000 plant species in more than 64 families, according to scientists at University of Florida Extension.
Ants like EFN, too.
So do a lot of other insects, including those hungry Gulf Fritillary caterpillars that eat everything in sight...and out of sight...
It's Sunday and he's having Sunday dinner--after having Sunday breakfast and lunch and snacks in between, thank you.
He's on his way to becoming a Gulf Fritillary (Agraulis vanillae) butterfly.
A European paper wasp, Polistes dominula, circles, attacks, and the non-battle is over within seconds. The caterpillar is defenseless. The wasp is hungry. There is not much left.
Indeed, there isn't much left when European paper wasps descend on a Gulf Fritillary population. They eat the eggs, the caterpillars, the chrysalids, and the adults, carrying food back to their colony. Protein. Predators. Predators with a Purpose.
Do they attack adult butterflies? They do. We recently shared one of our images of a European paper wasp (EPW) attacking an adult Gulf Frit; it appears in the current edition of the University of Wyoming's Barnyards and Backyards. See PDF.
EPW is a relative newcomer to America. Native to the European and Asian continents, it was first discovered in the United States in the late 1970s and has spread throughout the country. It's often confused with the native yellowjacket. How can you easily distinguish them? The EPW's antennae are orange.
Entomologist Whitney Cranshaw of Colorado State University described the European paper wasp as a nuisance pest in a 2011 scientific article published in Southwestern Entomologist. In the abstract, he noted that it has "colonized much of Colorado during the past decade and has emerged as a dominant species of nuisance wasp. It is impacting many types of prey species, particularly larval Lepidoptera. However, in western Colorado it is also a common pest in fruit orchards and can be very damaging to ripening grapes, Vitis vinifera L.; sweet cherries, Prunus avium (L.) L.; and other thin-fleshed stone fruits. This latter habit is unusual for a Polistes species."
The EPW is considered by many as a beneficial insect, especially when it targets the caterpillars of cabbage white butterflies, alfalfa butterflies and other pests. Butterfly enthusiasts are none too happy, though, when it preys upon the preferred butterflies, including monarchs, Western tiger swallowtails and Gulf Fritillaries.
Meanwhile, back at the Passiflora. There's a population explosion of Gulf Frits. 'Cats all over the place. 'Cats eating leaves, flowers and stems. it's a veritable meat market for wasps (and spiders, praying mantids and other predators). The drama continues...
Let's celebrate the Gulf Fritillary (Agraulis vanillae).
If you have a passionflower vine (Passiflora) in your yard, you've probably seen these spectacular orangish-reddish butterflies with silver-spangled underwings fluttering around--the males patrolling for females, the mating, the females laying eggs, the caterpillars hatching from the eggs, and the caterpillars munching and crunching until their last instar. Then you'll see them forming chrysalids, and butterflies eclosing.
The unseen world of Gulf Frits. The miraculous unseen world of Gulf Frits. Because it is.
That came to mind the other day when two passersby saw a dozen or so Gulf Frits heading into our yard.
"Look at all the butterflies!" one exclaimed. "I wonder what's attracting them."
"I don't know," the other said. "They must have a butterfly bush, maybe?"
"Oh, that's probably it. A butterfly bush."
Well, what's attracting them is the Passiflora, the host plant of the Gulf Frits. It's a congregation without a church. It's a gathering without a sermon. It's Nature at its finest. The Gulf Frits, aka "passion butterflies," lay their eggs only on the passionflower vine--mostly on the tendrils or leaves. The caterpillars will eat only Passiflora. The adults? They'll nectar on such plants as the butterfly bush, Mexican sunflower and lantana but will stay close to the Passiflora for mating and egg-laying.
If you're lucky, you'll see the entire life cycle--from egg to caterpillar to chrysalis to adult.
If you're really lucky, you'll see the tiny yellow eggs, which are about the size of the period at the end of this sentence. The yellow eggs turn from orange to rust, the color of the caterpillar inside.
The butterfly, found in many parts of the world, is a relatively newcomer to California. It was documented in Southern California, in the San Diego area, in the 1870s, according to butterfly guru Art Shapiro, distinguished professor of evolution and ecology at UC Davis. “It spread through Southern California in urban settings and was first recorded in the Bay Area about 1908. It became a persistent breeding resident in the East and South Bay in the 1950s and has been there since.”
Shapiro says it “apparently bred in the Sacramento area and possibly in Davis in the 1960s, becoming extinct in the early 1970s, then recolonizing again throughout the area since 2000.”
Today I explored the unseen and intricate world of Gulf Frits in our Vacaville (Solano County) backyard, managing to capture a few images. Then the unexpected happened. For the first time in the five years we've been rearing Gulf Frits, one landed on me! Apparently mistaking me for a plant, she touched down on my green t-shirt (which probably carried the scent of the passionflower vine). She was all set to lay an egg until....two males approached. Startled and a bit rattled--hey, I'm laying an egg here, leave me alone!--off she flew.
This time she vanished inside the depths of the passionflower vine.
With any luck, she'll do just fine in this congregation without a church, in this gathering without a sermon. She'll provide another generation that resembles the striking colors of those stained glass windows in a religious sanctuary.