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!
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...
When you're capturing images of butterflies, seconds count.
They're unpredictable. They move from fluttering to fleeting. And just when you're focused on where they are, they aren't there anymore. Where'd they go? Oh, over there!
Take the case of the Gulf Fritillary (Agraulis vanillae), aka the passion butterfly. Gulf Frits lay their eggs on their host plant, the passionflower vine (Passiflora). So it makes sense that males will patrol the vine. It's where the girls are.
And where the camera usually isn't.
And if you happen upon a mating pair, and hordes of other Gulf Frit males are disrupting the "passion," they'll take off, intertwined, for another spot. A little seclusion in "the bedroom," please, and then it's off to "the kitchen," where the nectar-producing flowers are.
This pair (below) found one another on the passionflower vine as other males bombarded them. They lumberingly headed for another spot, and the rest is history. Or her-story. Soon the female will be back laying eggs on the Passiflora, and the cycle of egg, caterpillar, chrysalid and adult will begin all over again.
These images were taken with a Nikon D800 equipped with the macro zoom lens, 70-180mm f/4.5-5.6D ED. Settings: ISO 800, f-stop, 13; and shutter speed, 1/640 of a second.
Seconds count. No, not just seconds. Fractions of a second!
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...
You gotta love those 'cats.
Gulf Fritillary caterpillars (Agraulis vanillae) are always hungry. They're as hungry as teenagers returning home from a marathon swimming meet or from a double-overtime basketball game. As soon as they step in the front door, it's off to the refrigerator. What's to eat? I'm starving! When's dinner?
Gulf Frit caterpillars are like starving teens. The 'cats will eat everything in sight--the leaves, buds, flowers and stems of their host plant, the passionflower vine (Passiflora). "Host plant" is a good word--you be the host, Passiflora, and we, the Gulf Frits, will eat it all. Everything.
In fact, Gulf Frit caterpillars will compete for food and knock one another around. When food is scare, they'll engage in a little cannibalism.
If you have a healthy passionflower vine and a good supply of Gulf Frits, chances are your plant will be skeletonized by the end of the season. The 'cats will eat heartily, form a "J," spin into a chrysalis, and voila! An adult butterfly will eclose. That's what butterflies do.
In a previous Bug Squad, we mentioned that the Gulf Frits are found in many parts of the world and arrived in California (San Diego) in the 1870s, according to butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology. They spread through Southern California in urban settings and were first recorded in the Bay Area about 1908, Shapiro says. They "became a persistent breeding resident in the East and South Bay in the 1950s and has been there since.”
Shapiro says the Gulf Frits “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.”
Some folks don't like Gulf Frits skeletonizing their passionflower vines. They grow them for the passion fruit and for their floral beauty. And when the Gulf Frits take over and decimate the plants? "We look like bad gardeners," lamented one UC Master Gardener.
Bad gardeners? Well, no. Good butterfly conservationists? Yes!