- Author: Kathy Keatley Garvey
Last weekend a little critter made its first-ever appearance in our family bee garden. It was neither a grand entrance nor a grand insect.
"A fly!" I thought, as I looked at its knoblike bristle or arista on the end of each antenna.
But its body--what little I could see of it before it winged out of there--definitely resembled a wasp. A Western yellowjacket (Vespula pensylvanica) or European paper wasp (Polistes dominula).
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at the UC Davis Department of Entomology and Nematology, identified it as a syrphid fly, genus Ceriana, family Syrphidae.
Talented Davis photographer Allan Jones captured an excellent photo of Ceriana in 2012. A full body shot: head, thorax and abdomen! His excellent image (second one, below) shows the distinguishing characteristics: two wings (fly), not four wings (bees, wasps), as well as the arista (fly) and the spongelike mouthparts (fly).
BugGuide.Net posted some excellent images of Ceriana on its site. Class: Insecta. Order, Diptera. Family: Syrphidae: Genus: Ceriana.
Ceriana is a genus of wasp mimics. Basically, it's a syrphid fly, a pollinator. It's also known as a hover fly or flower fly as it hovers, helicopterlike, over flowers before drops down to forage.
Would-be predators, no doubt, avoid Ceriana because of its coloration. "Oops, don't mess with that! That's a wasp!"
Picnickers who don't know a faux wasp from a real one would probably run from it, or swat at it.
"It's definitely a good mimic and probably gets a lot of protection from that coloration," said Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis.
So true!
- Author: Kathy Keatley Garvey
When you're trying to rear Gulf Fritillary butterflies (Agraulis vanillae), expect the expected: predators.
It doesn't take long for European paper wasps (Polistes dominula) to find the butterfly's host plant, the passionflower vine (Passsiflora) and prey. We've seen the wasps, with their long hind legs dangling, follow the butterflies as they flit from tendrils to leaves to lay their eggs. The wasps grab the tiny yellow eggs and squirming caterpillars and rip into chrysalids.
They'll attack adult butterflies, too, especially the crippled ones.
Then off they fly with bits of food--protein--for their colony. Wasps are carnivores (unlike their cousins, the honey bees, which are vegetarians).
The European paper wasp, so named because of its European origin, is relatively new to the United States. Scientists tell us that the P. dominula was not recorded in North America until 1981. P. dominula was first discovered in the United States in the late 1970s near Boston, Mass. This invasive species has since spread rapidly across the country. Entomologists worry that it is displacing the native species of Polistes wasps.
Have you ever seen these wasps attack other insects? Butterflies?
Last Sunday we were watching a crippled butterfly (no doubt crippled by a predator such as a bird or praying mantis) clinging to a Passiflora leaf as males tried unsuccessfully to mate with her. Eventually, the males all fluttered away and a European paper wasp patrolling the area zeroed in for the attack.
Like a hungry lion singling out a crippled gazelle from a stampeding herd, the European paper wasp knew just what to do.
- Author: Kathy Keatley Garvey
Your mother laid an egg, you hatched into a caterpillar, and you're eating as much as you can before you spin into a chrysalis and then emerge, as a butterfly, ready to start the life cycle over again.
You are not aware of the European paper wasp, its long legs dangling, moving through the leaves and eating the newly laid eggs around you. The wasp lurks in the deep, dark shadows as you finish one bite and reach for another.
Then you see the predator coming after you.
It does not end well for you. You have become protein for the wasp to feed its young.
For several weeks now, the European paper wasps (Polistes dominula) have wreaked havoc on the Gulf Frit population on our Passiflora. Sometimes they pair up in twos, sometimes in threes and fours, and once a horde of five descended
They follow the fluttering butterflies as they touch down on a leaf to lay an egg. Then they eat the eggs, kill the caterpillars, and tear apart the chrysalids.
European paper wasps are relatively new invaders from Europe; they were first spotted in the United States in 1981 in Massachusetts. They are now colonizing the entire country, taking over the native wasps' territory.
There's good news and then there's bad news. If you like having European paper wasps around to prey on the larvae of hornworms, cabbageworms and tent caterpillars, then you may consider them beneficial insects. But if you're trying to rear a few butterflies, such as the Gulf Fritillaries (Agraulis vanillae), then they're Public Enemy No. 1.
Studies show that they can also be cunning.
According to an article out of Michigan State University: "A Cornell University researcher has found that certain female wasps, without nests of their own, 'sit and wait' for an opportunity to adopt an orphaned nest or hijack a nest from another queen. These sit-and-wait female wasps prefer to adopt the most mature nests, probably because these nests will produce workers the soonest, and colonies with workers are very likely to survive. Once a queen adopts a nest she will eat the former queen's eggs and young larvae and replace them with her own eggs. The older larvae and pupae, which belonged to the former queen, are allowed to complete development and may eventually help rear the adopting female's offspring. Ferocious hunters, paper wasps feast on caterpillars."
"The nests are usually founded by a single Queen or Foundress, who starts her nest in May having hibernated as a mated queen throughout the winter often in the company of all the other mated females from their parental nest."
See photos of European paper wasps on BugGuide.net.
Meanwhile, we figure that only about 10 percent of the Gulf Frit eggs will ever make it into butterflies--no thanks to assorted predators.
But a few will make it, and what spectacular butterflies they will be!
- Author: Kathy Keatley Garvey
Be careful when you're harvesting an artichoke.
You might find a European paper wasp (Polistes dominula) hunting for a little protein, such as ants, flies and tiny bees to carry back to its nest.
Entomologist Whitney Cranshaw of Colorado State University writes in one of his fact sheets that "European paper wasps rear their young on live insects. They do not produce nuisance problems around outdoor dining that characterize scavenging species, such as the western yellowjacket. European paper wasps will sometimes feed on sweet materials, including honeydew produced by aphids. On rare occasions, they also may feed and damage ripe fruit."
Don't consider the European paper wasp a pest. "European paper wasps have become one of the most important natural controls of many kinds of yard and garden insects," Cranshaw writes. "Most commonly they feed on caterpillars, including the larvae of hornworms, cabbageworms, and tent caterpillars. Sawfly larvae are also commonly taken prey."
As its name implies, it's a native of Europe. Says Cranshaw: 'The European paper wasp is the common paper wasp of Europe. It was first found in North America in the 1970s in the Boston area. Since then it has spread rapidly to much of the northern half of the United States and British Columbia."
Volunteers at the Häagen-Dazs Honey Bee Haven at the Harry H. Laidlaw Jr. Honey Bee Research Facility, University of California, Davis, recently spotted a paper wasp nest on a lush growth of grey musk sage.
As the paper wasps tended and guarded their nest, honey bees, bumble bees and carpenter bees gathered nectar.
The bees: vegetarians. The wasps: carnivores.
- Author: Kathy Keatley Garvey
On the grounds of the Harry H. Laidlaw Jr. Honey Bee Research Facility at the University of California, Davis, something as simple as a freshly watered potted plant will do.
Without water to ventilate and cool the hive, the wax inside an overheated hive on a hot day will melt and the brood will die.
However, if you see a honey bee collecting water, you might also see a European paper wasp (Polistes dominula).
These wasps need water to mix with their saliva and wood fibers to build their nests (right). They also bring back water for the offspring and to cool their nests.
Honey bees stand on the lip of the container or on rocks or sediment. They don't like getting their feet wet. Not so with wasps.