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.
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
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.