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!
May 31, 2012
I've been spending a lot of time thinking about rats. Thankfully, it is not because I have a problem in my apartment! Unfortunately, for many people in L.A., rats are a serious pest, and it's not just one type of rat. The most serious rodent offenders in our cities are the brown (aka Norway) rat, Rattus norvegicus, and the black rat, Rattus rattus.
What species of rat is this?
Here on the North Campus we have camera trap images and footage of rats hanging out underneath the bridge. But what type of rat is this? Since Jim Dines, our Mammalogy Collections Manager, wasn't available, I decided to try and figure it out myself. Doing a Wikipedia search for brown rats, I came across a nice diagram that helped me to make an identification. What species do you think it is?
Comparison of the physique of a black rat, Rattus rattus,
with a brown rat, Rattus norvegicus, from wikipedia
Using this diagram I looked closely at the ears and the eyes of the rat. Based on the relatively large size of the ears and the eyes, I determined the above image was of a black rat rather than a brown rat. I showed the image to Jim and he confirmed that it was indeed a black rat!
Black rat (top) and brown rat (bottom) from the Museum collection.
Note the tail to body length ratio.
Regardless of the species, why do people hate rats? As I referenced in the introductory paragraph, rats are sometimes pests in our homes, but what exactly do people think about rats? I did a Google search for, "why do people hate rats," and this is what I found. "Cute or not they're germ-ridden disease carrying vermin who in addition, can cause untold damage. THAT'S WHY." I also found this: "Rats are pests to humanity, but I personally believe that people especially hate rats because they subconsciously identify with them and see them as a reminder of themselves." Finally, someone else wrote: "A lot of rat-hatred goes back as far as plague. Rats were responsible for the disease that killed thousands of people."
But, is plague a worry for us today in L.A.? Not really here in the city (I hear a collective YAY)! Firstly, according to the Centers for Disease Control and Prevention the last cases of urban, rat-associated plague occurred in L.A. in the 1920s. However, plague is present in L.A. County, and the principal mode of infection is from infected fleas living on wild rodents in rural areas. These rodents include California ground squirrels (remember the recent blog post?) and chipmunks! According to L.A. public health officials, "the major threat of plague to humans is in the rural, recreational and, wilderness areas of the Angeles National Forest, as well as the Santa Monica and San Gabriel Mountains." But, before you swear off recreating in our lovely parks forever, know that there have only been four cases of the plague in L.A. since 1979, none of which were fatal (another YAY for antibiotics and modern medicine).
P.S., Plague is actually caused by a bacteria, Yersinia pestis, that lives in the blood and other bodily fluids of fleas, rodents, and other mammals.