July 2, 2015
After three long years of planning, 45 arroyo chub were finally released into the Nature Garden's pond last week.
Arroyo chub (it's alive, don't worry!) held for a quick photo op before release into the pond! Photo by Richard Hayden. Arroyo chub, Gila orcuttii, are a native freshwater minnow found only in the coastal streams of Southern California, says Chris Thacker, Museum Curator of Ichthyology (fishes). They are classified as threatened in this native range and are noticeably missing from the lower reaches of the Los Angeles river. So, when it came time to think about fish in the Nature Gardens pond, all our scientists and educators wanted Arroyo chub.
The chub were transported from the Riverside Corona Resource Conservation District in an extra large cooler. Photo by Jason Goldman. Our philosophy about purposefully introducing animals into the Nature Gardens is pretty strict-we generally don't do it. However, we knew we were going to make an exception for fish in the pond. Why? Because, mosquitoes! Although we're fascinated by all nature here at the Museum, we are definitely taking a stance against breeding mosquitoes in our pond. Which is a good thing, because the Greater Los Angeles County Vector Control District would step in and solve the problem for us if we didn't. Their solution would involve releasing 6-10 mosquitofish, Gambusia affinis, into our pond. But, we didn't want mosquitofish, we wanted a fish that was native to Los Angeles, something that could tell a better story about nature in L.A.. Arroyo chub have a great story. According to Thacker, "these minnows were historically found in arroyos and rivers in Southern California, but are now only known from the upper reaches of our watersheds." This is true for the highly altered and concretized LA River, where the chub are noticeably absent. When Friends of the Los Angeles River studied the fish of the river in 2007, they found zero arroyo chub and 668 mosquitofish, more than any other sort of fish! Although, these non-native fish are helping us to keep mosquito-borne disease cases down, they're also impacting other creatures that live in our rivers and streams. Museum herpetologist (reptiles and amphibians), Greg Pauly explains, "the name mosquitofish makes one think they are highly specialized on mosquitos, when in fact they are actually broad generalists and consume native amphibian eggs and non-target insects." The chub on the other hand are much more effective at eating mosquito larvae and predate less often on the frogs, toads, and native insects we are trying to encourage in our waterways. Because we wanted to encourage as much biological diversity as possible in our pond–especially all those dragonfly and damselfly nymphs–we pushed for chub. So why don't vector control use chub instead of mosquitofish? There are a few reasons. Chub are much harder to rear in captivity than mosquitofish, and it's therefore easier for vector control facilities to keep up with demand. More importantly, as a native fish arroyo chub require permits from California Department of Fish and Wildlife for us to keep them. Interesting that no permits are needed for the non-native mosquitofish. So, if you want to meet our new arroyo chub, come on down to the Museum. Thacker advises you to be patient, "They are skittish little fish and like quiet spots in the pond, so they will often be hiding, but can hopefully be spotted with a bit of dedicated observation."
November 12, 2014
The coffin fly. Image courtesy of Kelsey Bailey. As you get into your car in the parking lot of the Trader Joe’s in Silver Lake in Los Angeles, you might just be within arm’s reach of cannibals. Not the human kind – but the insect variety. Inside a wasp that is buzzing around a nearby bush dwells a bug known as the twisted wing parasite. These tiny insects are genetically close to flies and resemble nothing so much as a small black speck. But placing that speck under a microscope reveals huge, orb-like eyes that, as entomologist Emily Hartop puts it, look like sinister purple boysenberries. Although the twisted wing parasite’s name comes from the seemingly malformed wings of the male of the species, the female has no wings. In fact, she has no legs, not even functional mouthparts – she is literally just a sac containing eggs and fat cells.
Twisted wing parasite. Image courtesy of Kelsey Bailey. When she is ready to mate, she partially burrows out of her wasp host’s rear end, exposing her head and shoulders. She sends out an alluring chemical scent, a pheromone, to attract her mate, who flies in from afar and expertly inseminates her behind the head. She waits patiently for her eggs to develop and hatch. Then, she becomes a host of sorts: Her larvae slowly devour her as they thrive. When they are ready to search for their own wasp hosts, they wriggle out from behind her head, leaving her shell-like exoskeleton behind. Each female twisted wing parasite can bear 2,590 offspring this way. (The wasp survives the entire ordeal relatively unscathed; its only scar is that it is now sterile.) This is one of the true tales of L.A. noir unfolding around you – down in the depths of the soil, around the corners of buildings, and under the bushes of Southern California’s dark underbelly. I know about these monsters because I study insects at the Natural History Museum, where I work alongside the entomologists and volunteers (we call them “citizen scientists”) who trap and find them. I can tell you that L.A. is no City of Angels so far as insects are concerned. Death Becomes Her Some of my favorite bugs congregate around dead bodies. One place you might find them is the Hollywood Forever Cemetery, possibly circling around the head of the Johnny Ramone statue. To the untrained eye, they might look like any old gnat. But each of these bugs has a pair of huge eyes that look like they’re covered in mesh, long slender legs, and transparent wings. Couples like to meet in the air and fall to the ground in a moment of insect ardor. They are Conicera tibialis, more famously known as coffin flies. After the mating pair has parted, the female fly locates dead or decaying tissue (by smell, scientists presume) so she can lay her eggs. She can burrow almost seven feet underground, which is good because, if she’s looking for human tissue, it is often, as the adage says, about six feet under. She lays her eggs in the nooks and crannies around the coffin, and lets her maggots do the stealthy work of sneaking into the actual casket. If all this seems like a lot of work, it is. Oftentimes these flies eschew the dead humans and instead go for easy pickings such as the pet dog you buried in the backyard last week. Murder in the L.A. River As the runners, bikers, and strollers make their way along the path next to the Los Angeles River in Frogtown, the water gurgles by and the bushes gently rustle in the wind. But this idyllic scene masks murders happening just beneath the water’s surface.
Dragonfly nymph. Image courtesy of Chris Goforth. Baby dragonflies, otherwise known as nymphs, are voracious predators. Measuring from the size of a peppercorn up to an inch and half, these muted brown bugs blend in nicely with the muddy bottom at this part of the L.A. River. When prey swims by – it could be a fish, a tadpole, or a dragonfly sibling — the nymph unleashes its hidden jaws-of-death. Within a microsecond, the jaws snap onto the stunned victim and pull it in to be eaten alive. Nymphs can consume multiple meals a day in the watery depths—they are true cold-blooded serial killers. Off With Their Heads Another of my favorite ghoulish insects was discovered last November in Glendale in the big yards of the big houses sitting snugly up against the Verdugo Mountains. There, a large ant serves as the mansion of tiny Pseudacteon californiensis, or the ant-decapitating fly. These ants, known as velvety tree ants, make for nice homes because they are larger than the usual black ants you find invading your cat’s food bowl or committing suicide in your freezer during a heat wave. And they also have curb appeal: a velvety black abdomen and reddish-orange thorax. Perhaps that’s why P. californiensis has evolved to infect this ant and no other.
Ant decapitating fly. Image courtesy of Kelsey Bailey. Instead of a U-Haul, the female P. californiensis moves into her host by inserting her needle-like egg-laying device (ovipositor) into a weak point between two of the ant’s abdominal plates. She lays one solitary egg and flies away. Inside the ant, the egg hatches, and the maggot journeys to the ant’s head, where it chews its way through various tissues. Eventually, the ant is decapitated and dies—and the adult fly emerges through the oral cavity in a scene reminiscent of a horror film. ‘Zombees’ Zombies are all the rage in Hollywood—but real zombified bees might actually be invading Los Angeles any day now. Since 2011, infected bees have been spotted from Seattle to Santa Barbara. We’re not sure if they’ve arrived here already, but we recently set out traps in the Natural History Museum’s Nature Gardens to find out. “Zombees” begin their lives as normal honey bees, Apis mellifera. But when they meet a tiny honey-colored fly with dark eyes known as the zombie fly, Apocephalus borealis, these bees begin living a nightmare. The tiny female zombie flies insert their needle-like ovipositor into the abdomens of their bee hosts. They typically deposit a number of eggs, which hatch into maggots after a few days. Up to 15 maggots can survive inside of one honeybee, eating the bee’s insides. Right before the maggots are ready to turn into pupae, the next stage of their development, the zombee is somehow inspired to leave its hive at night—for what some call a flight of the living dead. These zombified bees are attracted to light, circling porch lights or writhing under lit windows in the early hours of the morning. About seven days later, the maggots erupt en masse from the neck region of the bee. They then crawl a short distance away, pupate, and emerge as adult flies nine days later, ready to find their next victim. When I pull dragonfly nymphs out of the L.A. River, or when I look at a zombie fly under a microscope, I revel in the fact that I’m privy to a tiny world that often goes unnoticed. Some people are afraid of bugs – and if you know what they’re doing to each other, it’s not hard to understand why. But bugs define our city as much as people do. If we don’t understand their lives and worry about their future, we’re not planning for our own future, either. And in a town that’s full of sequels and remakes and adaptations, the true stories of their lives are much stranger than our Hollywood fiction. With special thanks to the Museum’s BioSCAN (Biodiversity Science City and Nature) staff, particularly principal investigator Dr. Brian Brown, who designed and implemented the study of L.A.’s insects that discovered many of the creatures highlighted in this article. For more information about BioSCAN, check out the project page. *This was originally written for Zocalo Public Square
December 23, 2013
Let's celebrate another year of L.A.'s AMAZING BIODIVERSITY. The benevolent blogger that I am, here are your gifts: Twelve Rattlers Rattling
Eleven Potter Wasps Piping
Ten Flies Decapitating (decapitating ants that is)
Nine Dragons Dancing (in the L.A. River)
Eight Mantids a Milking
Seven Planarians a Swimming
Six Lizards a Laying
Five Foxes Ring-ding-ding-ding-dingeringeding!
Four Glowing Worms (yes, they're glowworm beetles)
Three French Opossums
Two Turtle Newts
and P-22 in the Hollywood Hills
Here's to another year full of amazing Los Angeles nature discoveries! *P-22 image courtesy of the Griffith Park Connectivity Study
July 12, 2013
Many of you know I am a huge L.A. river fan. As a fan of the river and an advocate for river access, I was of course shocked and worried to hear about the fire that took place in the pilot recreation zone last Saturday.
The fire raged on a sandbar adjacent to the river bike path (image courtesy of Anthea Raymond). The fire was caused by a gasoline tanker that crashed in the interchange tunnel between the 2 freeway and Interstate 5 (incidentally causing some of the most heinous traffic some of us have experienced in a long while). After it overturned, some of the 8,500 gallons of gas it was transporting leaked into a storm drain and traveled about half a mile into the river. The resulting fire was thankfully constrained to a sandbar located at the terminus of the storm drainage system, and according to California Department of Fish and Wildlife spokesperson Andrew Hughan, "There's very little to no environmental damage to the L.A. River." YAY! This news makes me particularly happy as this is one of the most wildlife-rich stretches of the river, and consequently one of my favorite spots to enjoy it. Literally, I was enjoying it only a week earlier, as I paddled by the area that caught on fire with the folks from L.A. River Kayak Safari.
Posing for a picture at the end or our kayak adventure! Not only was this one of the most fun things I've ever done on the river (sorry Mummy, but going down rapids in a kayak was way more fun than the Mother's Day picnic we had there), I also got to experience some wildlife I'd never seen in this urban riparian area before. The highlight of the trip was seeing my first Mexican Amberwing dragonfly, Perithemis intensa:
Male Mexican Amberwing, image courtesy of Bill Bouton. This dragonfly is one of the smaller of our region, with a wingspan measuring just over an inch and a half. Just like other dragonflies, it relies on water sources such as ponds and slow moving rivers to lay their eggs in. Female amberwings lay eggs in jellylike masses just above the waterline, as soon as water touches the eggs they literally explode out in different directions. This helps out, as after hatching dragonfly larvae can be cannibalistic on their bretheren. So much for peace and harmony on the river! The larvae spend a few months developing in the murky waters, eating what they can catch with their bear trap-like jaws, and in turn, escaping from predators like fish and frogs. When they're ready, the larvae emerge from the water and find a nice reed or stick to hang out on. They slowly crack open their exoskeleton and the adult dragonfly emerges, soft and drably colored. In a few hours they inflate their wings, harden their exoskeleon, and develop their more colorful selves. Then they'll zip off looking for a mate to repeat the whole cycle— provided they don't get eaten by a bird or an overly acrobatic fish! As you can imagine fire, gasoline, and dragonflies don't mix very well. Let's keep our fingers crossed that next time an accident like this happens the river will be just as lucky.