November 30, 2012
Recently, our garden staff has been finding LOADS of grasshoppers, but what are they all doing here? Are grasshoppers good for our gardens, or are they destructive like the plague of locusts (a swarming variety of grasshoppers in the family Acrididae) that appear in the Bible? On November 14, I snapped a decent picture of a grasshopper hanging out on a pitcher sage plant, Lepechinia fragrans. I thought I'd have a crack at identifying it, and hoped that, through the process, I'd be able to figure out what exactly they're doing in the garden.
Not a bad picture for my camera phone! Armed with a trusty book, the Field Guide to Grasshoppers, Katydids, and Crickets of the United States, I began my quest. It was a long and arduous quest, seriously! I spent almost an hour (okay, I know, I'm prone to hyperbole) going through the pictoral key, comparing my photo with the beautifully drawn pictures, and then cross-referencing with the species accounts, and range maps (they really helped me eliminate quite a few species straight away). Alas, it was all to no avail! Not to be outdone by a "lowly" grasshopper (am I a dork because I couldn't write lowly without quotes? I don't want the grasshopper to feel bad), I turned to the INTERNET! Bugguide.net to be exact. I submitted the above picture to their ID request section on November 20, at 11:55am. Eight days, 10 hours, and 17 minutes later, the quest was over. Thanks to David J. Ferguson for the species identification, and a shout out to my homie Eric R. Eaton for helping too! This is a female Melanoplus yarrowii grasshopper, a.k.a. Yarrow's spur-throated grasshopper. Okay, so now I had an identification. "So what," you may ask? Well, first and foremost, I felt vindicated. This species wasn't even in the field guide I was using, no wonder I couldn't ID it! Secondly, now that I knew the name, I could find out what this bug was all about. What I discovered is that this grasshopper is indeed very closely related to the plaguing locusts of yore. I also found out that, in the late 1860s, we had our very own plague of grasshoppers right here in Los Angeles, and it lasted on and off for almost three years. According to Brian Brown, Curator of Entomology, the grasshoppers responsible for the plague was most likely Melanoplus devastator, though there aren't any actual specimens for us to examine to be sure. Whatever the exact species, these grasshoppers were apparently pretty devastating. "When they had devoured all vegetation where they originated, they took flight and, flying with the wind moved in great clouds towards the east –like the locusts of Egypt, devouring everything in their course. When the destroying hosts reached the Calle de Las Chapules, the vinatero knew his grape crop for that season was doomed. The voracious hopper would not leave a green leaf on his vines, and the vineyardist considered himself fortunate if the destroying host did not devour the bark as well as the leaves." That's JM Guinn, author of The Plan of Old Los Angeles and the Story of its Highways and Byways.¹ The Calle de Las Chapules he is referring to is the former name of part of what is today Figueroa Street. That's right, it was called Grasshopper Street. Next time you're stuck in traffic on Fig, just imagine a massive swarm of grasshoppers descending on your car, I assure you, it will take away any road rage you might have! Thankfully, the Yarrow's grasshopper I found is not of the swarming locust variety. It does feed on plants, and is likely chowing down on various shoots and leaves out there in our garden. As far as the gardeners can tell me though, they're not causing much damage. So we're leaving them there to live another day, eat some more leaves, lay a few eggs, pose for a few more pictures, and maybe a few of them will become lunch for a hungry bird! ¹ From the Historical Society of Southern California's Annual Publication Volume 3, 1893-96. *Special thanks to Margaret Hardin, Curator of Anthropology for information on our Los Angeles grasshopper plague; Brian Brown, Curator of Entomology for identification of said grasshopper, and to Jonathan Gillet, Gallery Interpreter, for giving me the lead to the L.A. plague story!
August 25, 2011
This week I have renamed Sam (NHMLA's media producer for Nature Lab) Spider-Man! He's been out and about carefully sticking a mechanic's device into spider homes, so visitors to our Spider Pavilion can get a view into spider lives, like never before.
Funnel web spider, family AgelenidaeWhy you may ask? It's all in an effort to offer something new and interesting to Spider Pavilion visitors, and to test out ideas we have for media content in our upcoming Nature Lab exhibit. So Sam has been trekking around hillsides in the Santa Monica Mountains trying to find inhabited funnel webs. Some hillsides are better than others. The best ones are covered with hundreds of webs, like miniature spider cities. When Sam finds a good web for filming he sets up his equipment and gently probes into the funnel to see if anyone's home. He's using a borescope, an optical device used by mechanics to inspect hard to see parts of engines. Sam has also been setting up HD camera traps above the funnels to catch spiders in the act.
Sam using the Borescope Check out this bug war: Spider versus Grasshopper!To see more of the hidden lives of spiders visit our Spider Pavilion, opening September 25.
August 5, 2011
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.