Twelve Days of Christmas 2012

Since tomorrow is the twelfth day of Christmas, I thought I'd give you your belated gifts. Of course they're all part of L.A.'s surprising biodiversity, yes even those turtle wasps!

Twelve weevils wandering

Eleven pepsis wasps piping

Ten spiders-a-leaping

Nine ground squirrels dancing

Eight ants-a-milking (though technically they should be milking aphids)

Seven spittlebugs-a-spitting

Six roaches-a-laying (down that is)

Five under wings

Four warbling birds

Three French (phorid) flies

Two turtle wasps

And a hawk in a pear infested pond

Wishing you a happy New Year...what urban nature will we find this year?

Do Wasps Have Free Will?

We found a new wasp species in the North Campus. The Great Golden Digger Wasp, Sphex ichneumoneous, is an impressively large (approximately one inch long), and active solitary wasp. Although many see a wasp this large and brightly colored—the orange and black combo usually tells us to "stay away"—this wasp is not aggressive and is very rarely observed stinging. Solitary Hymenopterous insects (those in the order Hymenoptera, aka bees and wasps) are not prone to stinging the same way social species are. This is because they don't have a hive to protect.  

Great Golden Digger Wasp feeding on milkweed nectar

The Great Golden Digger Wasp is actually a beneficial insect in our gardens. Here's how: 

• They are great hunters. Their scientific name ichneumoneous, is Greek for tracker.
• Adults feed on nectar and are often seen foraging on flowers.
• When a female is ready to lay eggs, she digs up to six nests in exposed soil.
• When she is ready, she captures a cricket, grasshopper, or katydid (yay, pest control)! She paralyzes the insect by stinging it, and then takes it to the nest. 
• When she gets back to the nest, she goes in to check that everything is okay. She then emerges and drags the paralyzed insect into the hole. There she lays one egg on each paralyzed insect.
• The eggs hatch after two to three days and begin to feed on the paralyzed insect.
• After a few weeks to many months (depending on the time of year the egg was laid and the weather) the larvae metamorphose into adults and carry on the life cycle.

Free Will Hunting

In the 1980s, cognitive scientists, Daniel Dennett and Douglas Hofstadter, used these wasps' unthinking deterministic (aka pre-programmed) behaviors to illustrate the meaning of free will. As described above, female S. ichneumoneus, check their holes before dragging the paralyzed prey item into it. Scientists tested this behavior in a controlled environment by moving the prey item while the wasp was inside the nest. When the wasp emerged, she would relocate the prey, drag it back to the nest, and then check the nest again (even though she had already done it very recently). The experiment was repeated up to 40 times, and each time the wasp would re-check the nest. 

In Dennett's 1984 book, Elbow Room, he used this behavioral study as an analogy to the opposite of free will (coined sphexish by Hofstadter), i.e. futily repeating the same actions over and over again in a pre-programmed manner. In contrast, we humans have the ability to recognize futile behavior, exercise our free will to change something, and hopefully disontinue futile activities. YAY! He even coined the term antisphexishness, the state of free will.  Try dropping that one in your next conversation with an intellectual and see what happens!

Paper Wasps Sting Museum Taxidermist!

When Tim Bovard, the Museum's taxidermist, told me about getting stung by wasps on the fourth floor patio, I had to investigate, especially since I sometimes eat lunch up there. During a much needed afternoon break from my computer, I went in search of the offenders.

What I found on my afternoon foray were some large and impressive nests, definitely worthy of a blog entry. So of course I asked Sam if he would take pictures for me, and I went to work identifying them. 

Common paper wasp nest, Polistes exclamans

The species living on our patio are Common Paper Wasps, Polistes exclamans, which have a widespread distribution through much of the southern United States. These insects construct a papery nest from fibers they gather off dead wood or plant stems. Next time you see a paper wasp on a wooden fence realize it might be chewing off tiny pieces of wood which they will mix with their own saliva to make paper! The nests are umbrella shaped and generally built under eaves or porches, or in similarly sheltered locations. Unlike yellowjackets and hornets, paper wasp nests are not enclosed in a papery shell, which give a really good view into the individual cells.

A view into a brood chamber, can you see the larva?

Sam was also able to get some great video footage of the wasps at work. In an effort to provide the best video documentation ever, Sam nearly sustained a few stings himself. Luckily the wasps went for the video camera instead!

Waiter There's a Wasp in my Fig!

A couple weeks ago we had the second round of our North Campus insect survey. Fifteen Museum staff tromped around the North Campus to see what insectuous wonders we could collect. Although we found some notably large specimens, the largest being a 3-inch bird grasshopper (Schistocerca sp.), the most interesting find was actually something a lot smaller. Much, much smaller in fact: a minute fig wasp about 2 millimeters in length!

Female Fig Wasp, Pleistodontes sp.

Fig wasps belong to the wasp family Agaonidae and as their name implies, they have a life history intricately linked with fig trees, family Moraceae. In fact fig trees can not produce figs without the wasps, and the wasps can't reproduce without the figs! The way this mutually beneficial relationship works is quite astonishing, especially if you take a journey to the core of a ripening fig!

Journey to the Center of the Fig

It all starts when a mature female fig wasp enters the synconium (an immature fig if you will) through its natural opening, called the ostiole. This sounds really easy when you think how small these wasps are, but nature has not made it easy on the fig wasp, as the opening is actually too small for the adult wasp to enter without damaging herself. It's so small that the fig wasp often loses her wings and much of her antennae as she struggles through the opening. To enable passage through the ostiole, the underside of her head is also equipped with spines that help to get a grip as she's going through the hole (see image above).

Once inside the synconium she passes over the fig's female flowers and inadvertently deposits pollen from the male flowers of her original host tree. She then deposits her eggs in the cavity. Her business being done, she dies. The Pleistodontes fig wasp we found is, interestingly, not a pollinator of edible figs. Instead, it is a pollinator of ornamental figs which can be found in backyards and parks across Los Angeles.

Once pollinated, the fig fruit begins to develop, consuming the wasp's dead body in the process. The eggs hatch and the larvae consume small parts of the developing fig. After the larva eat enough fig, they pupate and finally emerge as adult male and female wasps. The wingless male wasps have only two functions to perform in their short lives—to mate and to escape! Finding a mate inside the fig isn't too difficult for the male wasp as all of his sisters are stuck inside the fig with him (remember how small the ostiole opening is). After he mates with at least one of his siblings (or offspring from another wasp), he begins digging a tunnel to exit the fig. This tunnel is the escape route that the female wasp uses to exit the fig, but not before she picks up pollen from the male flowers. This pollen will eventually pollinate the developing fig she visits to lay her own eggs in, and thus the life cycles of both fig and fig wasp continue. 

All I can say is WOW! Nature is weird, wonderful, and so cool!

Thanks to entomology curator Brian Brown for identifying and photographing the wasp.