November 18, 2013
I just found out we have ant-decapitating flies here in Los Angeles! Dr. Brian Brown, the Museum's Curator of Entomology and one of the world's foremost experts on flies, made a chance discovery by looking right under the nose of an unsuspecting USC student. It all started last Friday, while we were enjoying a nice stroll through the Nature Gardens. First, we checked out the Malaise trap that Brian and his staff set up as part of the BioSCAN project, which aims to survey the insect biodiversity here in Los Angeles. Then, we headed into the Nature Lab to see insects from this trap, and the 25 others that have been placed all over Los Angeles, being sorted.
As we got close to the demo table, Brian was suddenly transfixed. He'd seen something interesting on the screen that shows visitors the insects our scientists are sorting under the microscope. By some amazing coincidence, the USC student who was sorting a sample collected in Glendale, just happened to be looking at a phorid fly. Phorids, aka humpbacked flies, are the group of flies that Brian studies, and according to him, they are a mega-diverse family. How mega, you might ask? Apparently, there are estimated to be 40,000-50,000 species of phorid flies, and only 4,000 have been described by scientists so far. Wow!
But, it wasn't just any phorid fly. After taking a look through the microscope himself, Brian nonchalantly walks back over to me and said, "Yep, it's an ant decapitating fly." Whoa, what? I had no idea we had ant-decapitating flies (ADFs) here in L.A.! How could he have neglected to mention this exciting fact during all of our insect musings? Sure he's regaled me with stories of ADFs from Costa Rica and Brazil, always with devilish decapitating detail. But, he never mentioned we have phorids in the genus Pseudacteon, also known as fire ant decapitating flies, here in L.A. Fire ant decapitating flies do just as their name implies. When a female is ready to lay an egg, she locates an unsuspecting worker ant and injects her egg into the thorax. As the larva develops it migrates into the head capsule and molts a number of times. Through this entire process the ant behaves normally. However, just before pupation, the maggot begins to consume the tissue inside the ant's head, which causes the ant to act oddly, and soon after, to expire. The head falls off and the mouth parts are pushed out, so the oral cavity is clear. As the larva pupates, the adult fly emerges from the now-clear oral cavity of the ant. How's that for an alien ant birth? Later that day, Brian wrote an e-mail to the homeowner where the trap was located in Glendale: "Your backyard trap got something unusual- a phorid fly (the group of insects I study) of the genus Pseudacteon. The flies in this genus are all ant parasites, developing in the ant's head, and are referred to as 'ant-decapitating flies.' Usually, in suburban areas, the ant hosts of Pseudacteon are eliminated by the introduced Argentine ant, but you must have (or be close to) a healthy native ant fauna!" This, as Dr. Luis Chiappe, Vice President of the Museum's Research and Collections Department, put it, "is the power of science!" The presence of this parasite, allowed Brian to infer the presence of the host. If we went out to Glendale today, we'd likely be able to find native fire ants somewhere close by! And I know you all dying to join me on that adventure.
October 2, 2013
Guess what? We have bats in the Nature Gardens! And we have proof, thanks to two of our intrepid scientists, Jim Dines and Miguel Ordeñana. Here's the proof, in sonogram format:
Keep reading to find out what bat these blue and green blobs belong to! Here's what Jim and Miguel have to say about our bat detector: "Colleagues: Last Friday we installed newly acquired bioacoustic monitoring equipment near the pond in the Nature Gardens in the hope of documenting nocturnal aerial visitors. Yes, we’re talking about bats! Beyond expectation, our equipment has already recorded two different species of bats foraging in the Nature Gardens: the Mexican Free-tailed Bat and a Myotis species. Detectors like the one we are using are a great way to passively monitor for bat activity. The device records the ultrasonic echolocations that bats make, allowing us to later convert them into sonograms (graphic representations of the sounds) that can be analyzed using special software. Since bat echolocations are species specific, we can identify the species of bat based on their sonogram. Attached is a sonogram from the Free-tailed Bat we recorded. More than 20 species of bats occur in the greater Los Angeles area, but most of them are thought to inhabit non-urban habitats like outlying deserts and mountains. The Free-tailed Bat and the Myotis Bat we just documented are new records for Exposition Park. They join just one other bat species previously documented here based upon prepared specimens in the Museum’s mammal collection: the Hoary Bat. Jim Dines, Mammalogy, Collections Manager Miguel Ordeñana, Lead Gallery Interpreter, Field Biology" After making this awesome discovery, Miguel added the sonogram as an observation to our L.A. Nature Map!
Mexican Free-tailed Bat, Tadarida brasiliensis
September 24, 2013
We've added a new insect delicacy to the menu for the dwellers in our Spider Pavilion. That's right, usually the ladies (and few gents), that call the spider pavilion home, get fed butterflies, crickets, and flies, but as of this week we've added green lacewings!
Whitebanded Crab Spider, Misumenoides formosipes, getting ready to eat a Green Lacewing, Chrysoperla rufilabris. Green lacewings, belong to the insect order Neuroptera, also known as nerve-wings. Not only does this mean that most people have never heard of them, it also means they have complex designs, or "nerves" in their wings. Some might think that this translates into flying well, but alas, this group of insects are notoriously poor fliers. However, what they lack in flight, they make up for in mouthparts. Big scary-looking mouthparts! Especially, if you're a small soft-bodied garden pest. I mean, check out the green lacewing's cousin the dobsonfly. Those are some killer mouthparts!
Male Dobsonfly, Corydalus cornutus, photo by Dehaan Immature green lacewings (aka aphidlions) are such good predators, they have to lay their eggs on stalks, or they'd get cannibalized!
Not a very good picture, but you get the idea! Gardeners and farmers have learned to capitilize on the lacewing's voracious appetite, by using them as biological control agents. They eat, on average, 200 aphids a week, and can also be found eating other insect eggs, mealybugs, thrips, immature whiteflies, and even small caterpillars. So next time you have a pest infestation in your garden, hope you have some Green Lacewings out there making friends with those ladybugs!