Faces of BioSCAN: Research with the Remarkable Regina Wetzer

Photo by Phyllis Sun

Photo by Phyllis Sun

This week, I am pleased to better acquaint you with BioSCAN’s Co-Principal Investigator, and Associate Curator & Director of the Marine Biodiversity Center, Dr. Regina Wetzer. Regina was a natural fit for the BioSCAN project. She is a marine biologist with a passion for taxonomy and biodiversity. She is also an accomplished ambassador — she works closely with both professors and students at USC and has colleagues across disciplines and around the globe. She understands deeply how collaborations allow researchers to accomplish bigger, greater goals than what they could achieve individually. As Co-Principal Investigator of this project, she supervises much of the day-to-day activity of the BioSCAN lab — including advising our many USC students on their BioSCAN-related research projects. She also manages the lab with impeccable organization and style, and plays a key role in putting on events like last weekend’s soirée for our BioSCAN site hosts.

Regina grew up here in Southern California — in fact, her grandfather used to push her stroller through the Exposition Park Rose Gardens next door to the Natural History Museum. She earned degrees at both Loyola Marymount (B.S. Biological Sciences) and Long Beach State (M.S. Biological Sciences/Invertebrate Zoology) before taking a job with a marine supply company. There, she worked for Rim Fay, Southern California’s answer to Dr. Ricketts from Cannery Row. Eventually, fate led her back to the Natural History Museum here in Los Angeles. As a curatorial assistant, Regina found herself smitten — with crustaceans. After moving to the San Diego Natural History Museum for a time, she traveled across the country to get her doctorate working on crustaceans at the University of South Carolina.

Regina’s work in recent years has been on the taxonomy of crustaceans, focusing on the isopod family Sphaeromatidae. She has been working on this group’s phylogeny and mate-guarding behaviors since 2002 — with work around the world including East Africa and the Great Barrier Reef. It is a testament to her dedication that twelve years after this project began, Regina is still working hard to answer the questions originally posed when she started her work on this particular phylogeny.

Photo by Dean Pentcheff

Photo by Dean Pentcheff

Regina’s work has taken her to South America, the South Pacific, Australia, and even Mongolia (photos above and below — and, yes, landlocked countries have crustaceans, too!), but she speaks most fondly of her extensive travels in Baja. Part of her affinity for the peninsula comes from her fascination with organisms that are adapted to life in extremely harsh conditions, including desert flora and fauna. The fantastic landscapes of the San Felipe and Vizcaino deserts of Baja, with their boojum trees, ocotillo, and giant cardon, intrigue and delight Regina. These are magical lands for all who visit them, and Regina is lucky enough to have visited them many times.

Photo by Dean Pentcheff

Photo by Dean Pentcheff

In addition to her prolific body of scientific work, Regina is a fantastic and passionate cook, an avid gardener of cacti and succulents, and a devoted fan of gypsy music (she grew up with a father who plays accordion!). Her favorite vacation destination is her beloved Baja “Boojumland” (although she’s in Tibet as we post this!). She’s an amazing leader, an excellent scientist, and a fascinating human being — we’re incredibly lucky to have her on the BioSCAN management team!

The Mesmerizing Eyes of Eristalinus taeniops

Photo by Dr. Brian Brown

Photo by Dr. Brian Brown

This week, we bring you a visual treat from BioSCAN’s Principal Investigator, Curator of Entomology, and Photographer Extraordinaire, Dr. Brian Brown. His beautiful photo (above) of Eristalinus taeniops was taken in the NHM’s Nature Garden, home to BioSCAN Site #1. This species is commonly known as the Stripe-Eyed Flower Fly, from the family Syrphidae, commonly called Flower or Hover Flies from their habit of hovering hummingbird-style over flowers in search of nectar. Although syrphid flies are quite common in the BioSCAN traps, this particular species has not yet been captured by our project. Dr. Jim Hogue, also an entomologist and photographer as well as a BioSCAN site host, speculated that this fly is simply too strong a flier to be easily corralled into death by Malaise trap.

The entomological equivalent of “The Ugly Ducking”, the larvae of the stunning Stripe-Eyed Flower Flies are filth-dwelling Rat-Tailed Maggots. The “rat tail” is actually a telescopic breathing tube that allows larvae to mature in stagnant, and often polluted, water (and other moist substrates lacking in oxygen). The tube allows them to “snorkel” at the surface to breathe.

Also on the list of this fly’s unsavory larval habitats, rare cases of human intestinal myiasis — where larvae develop inside the human gut — have been documented for this group. The breathing tubes of the maggots, in this case, would be located in close proximity to their host’s anus to allow them to breathe.

Despite their distasteful beginnings, the Stripe-Eyed Flower Flies certainly turn out to be magnificent adults. Not only are they amazing honeybee mimics, but their striped eyes are absolutely hypnotizing. This pigmentation may serve an optical purpose, but more research must be done on this group before conclusions are to be made.

Photo Copyright by Dr. Jim Hogue (used with permission)

Photo Copyright by Dr. Jim Hogue (used with permission)

If you haven’t seen the Stripe-Eyed Flower Fly buzzing around your yard, keep looking! The first California record for the species was in 2006 from Orange County. Three years later only a single specimen was found when Dr. Brown and Dr. Hogue worked on local Flower Flies for the booklet “Flower Flies of Los Angeles County“. That single specimen was from Dr. Hogue’s Eagle Rock backyard, which is now a BioSCAN site! Above, you can see another beautiful photograph of this species, this one taken by Dr. Hogue.

Originally, Eristalinus taeniops was from southern Europe, Africa and the Middle East. Introduced species can sometimes create issues for native flora and fauna, but it doesn’t appear that Eristalinus taeniops is creating any problems. We’re glad, because it sure is a stunning addition to our Flower Fly fauna!

The Faces of BioSCAN: Photography with Kelsey Bailey

Photos by Kelsey Bailey

Photos by Kelsey Bailey

BioSCAN Buzz is excited to bring you the first in a new series of blog features: “The Faces of BioSCAN”. We will be interspersing these posts, illuminating the amazing folks we have working behind the scenes, with continued coverage of exciting news from the project.

This week, we begin our series by featuring the woman behind the amazing insect photographs you see on the blog: Kelsey Bailey.

Photo by Phyllis Sun

Photo by Phyllis Sun

Kelsey is a senior political science student at USC, minoring in photography and social change. After graduation, Kelsey aspires to find a job that will utilize her diverse talents and allow for travel. She has the ambitious goal of becoming a photographer for National Geographic; from what we’ve seen she’s well on her way to achieving success of that caliber!
Kelsey’s interest in photography encompasses all elements of the craft, from the technical to the artistic. Her art history and photography classes have left her intrigued and inspired about the “many different dialogues about time, legacy, representation, technology, mortality” that photography opens up. She is constantly challenging herself by working on both the technical specimen photography for BioSCAN and fine art, conceptual photography. She finds her job particularly exciting when the two intersect, which we like to think happens with our beautiful insect specimens.

In her work with BioSCAN, Kelsey expressed her excitement that she gets to reveal a microscopic world through her photography: “To the naked eye, insects appear to be indistinguishable black specks in a petri dish, using a camera and a microscope I get to expose them as remarkably diverse creatures with intricate structures and vivid colors. Photography is an effective way to convey this biodiversity to the public as well as inviting people to take a peek at a microscopic world.”
Kelsey also spoke of the challenges of shooting insects: “They’re ridiculously small and sometimes difficult to physically handle. It’s been somewhat of a struggle to develop a process for photographing them, but it gets easier over time.” Kelsey’s process involves photographing the insects under a microscope with a camera connected to a computer. At high magnification, she must take a series of photographs at different focal lengths, and then “stack” them using special software. This allows her to create composite photos that have the entire depth of the insect in focus.

Kelsey is well versed in dealing with the many challenges of insect photography. She photographs specimens both dried and in ethanol; each provide very different obstacles. Reflections and refractions are constant hurdles one must face when photographing through a liquid, or photographing insects, which often have reflective surfaces. Her favorite insect to photograph? So far, Kelsey’s favorite photography session was with the asilid, or Robber Fly, which is the top left image in the collage above. Kelsey loved that the Robber Fly was “such a theatrical little monster!”
Outside of BioSCAN, Kelsey loves music, politics, other art forms, the great outdoors, pouring cream into her coffee, making things with her hands, and beer tasting. Just recently, Kelsey ran the LA Marathon which she considered a “quite monumental” personal accomplishment (we agree!). We can’t wait to see what Kelsey does next, and we’re so happy we can share her talents with all of you!

Flat-headed Fig Invaders from Outer Space!

Photo credit: Kelsey Bailey

Photo credit: Kelsey Bailey

Disclaimer: To our knowledge fig wasps are not really from outer space, they just look like miniature aliens.

To understand the tiny wasps in the family Agaonidae, you must first understand their inverted-flower “spaceships of reproduction”: figs. A fig, although it masquerades as a simple fruit, is actually an inside-out inflorescence (cluster of flowers). This inflorescence, once pollinated, becomes an infructescence (cluster of fruits) that contains the fig tree’s seeds. Pollinating this “calzone of the flower world” is no easy task: enter the fig wasp.

These flat-headed wonders of fig pollination measure out at a slender two millimeters in length, and have an obligate mutualism with fig trees —meaning the wasps and trees cannot live without the other. The ultimate example of a “pollination syndrome”, where a flower’s shape, size, coloration and other traits have evolved to facilitate pollination by a particular taxon, a fig can only be pollinated by this single family of miniature wasps. Despite their highly specialized co-evolution, the pollination of a fig tree by its wasp friends is not a cakewalk.

Pollination is done exclusively by female wasps. These lovely ladies leave the figs of their youth to seek out new figs in which to lay their eggs. They hone in on the scent of a new tree, which is often species-specific (one species of wasp paired with one species of tree), and once they have it located, they must enter the fig to reach the flowers on the inside. This is a task of perseverance: the fig has only one small opening, called an ostiole, where the wasp can make her entrance. This small tunnel to the inner paradise of the inflorescence is lined with highly-modified leaves, called bracts. The narrow tunnel and its lining make entering the fig a tight, tortuous squeeze. Female fig wasps have a flattened shape to facilitate squeezing through this opening. They also have special teeth on the bottoms of their heads and on their legs to help them wiggle through. Often, these hard working women lose their wings and antennae in their struggle to gain entrance to the inner sanctuary of the fig. Once inside, however, their plush floral surroundings are the perfect site for egg deposition. As the wasp moves about laying eggs into the ovules of the flowers, she deposits pollen that she picked up in the fig of her birth. Any ovule that does not receive an egg, but does receive pollen, becomes a seed for the fig tree’s reproduction.

The eggs mature inside the ovules of the fig’s inner flowers, creating galls. Once the larval wasps hatch, they feed off of the inner tissue of the flower until they are ready to emerge. Males and females emerge simultaneously, and mate inside the fig. Males are wingless and have two functions: mate and chew through the fig to create an escape for females. They die shortly thereafter. The females use the tunnels made by their mates to escape and go find a fig “spaceship” of their own.

We know you are now wondering; am I eating fig wasps when I eat figs? The answer is: possibly, but they would be a different type of fig wasp than this alien-looking flat headed type. This particular genus of fig wasp, Pleistodontes, is a genus native to Australia that came over with ornamental fig trees. Because these wasps pollinate ornamental figs, they won’t be found in commercial varieties in the store.

Other fig wasps may be in commercial varieties, but different varieties are produced differently. There are fig trees that have been bred to produce figs without pollination, in which case wasps would not have an association with those breeds. There are also both monoecious and dioecious types of fig trees. In monoecious varieties, you will end up with figs that contain both seeds and wasps, whereas in dioecious varieties the male trees produce figs with mostly wasps (due to short styles that allow females to lay eggs in the ovules easily) and female trees produce mostly seeds (due to long styles that prevent egg implantation but allow pollination). If a fig comes from a male plant and is full of galls, you would certainly notice it. In female plants that have been pollinated (but not laid in) there may have been one, or several, female wasps that entered but never left. Luckily, figs produce enzymes that can break down any adult wasps that perish inside the developing infructescence.

That “crunch” when you chew a fig? Rest assured those are seeds, which are considered a desirable trait in figs. When the fig was first being grown in California, we did not have the fig wasp here and our figs did not have those wonderfully crunchy seeds. It took a few years, but scientists finally figured out the problem — and we’ve been happily munching on crunchy figs ever since, all thanks to the introduced fig wasp.

The Twisted Adventures of the Scintillating Strepsiptera

Photo by Kelsey Bailey

Photo Credit: Kelsey Bailey

Shrouded in dusky, voluminous wings, a male strepsipteran catches the pheromone trail of a potential mate. With only hours to live, his first and only priority is to reproduce; his boysenberry-like eyes gleam as he heads upwind.

As his hideously twisted hind wings plow through the air, lifting him into the sky, he reflects on his life. Born inside his mother’s body cavity, this strepsipteran spent his early days with his siblings, consuming his mother from the inside out…

Without eyes, wings, or legs, his dear mother had made her home in the abdomen of a wasp. She had found this host when she was but a small, mobile larva, and burrowed into its abdomen. There she had matured, cloaking herself with host tissue grown specially for her protection. As a young maiden, she exposed her upper body between the plates of the wasp’s abdomen, leaving a trail of pheromones for her Prince Charming to follow. When our male strepsipteran’s father made his appearance, he pierced his mate just below her head in a romantic act lasting mere seconds. Nothing says “love” more than hypodermic insemination: this is where baby strepsipterans come from.

And so our hero was born, and he and his siblings nibbled away at their mother until she was but a shell, and he was old enough to leave the safe confines of her body. He ventured out in search of a new live host, and latched onto a wasp host of his own. Once in his new host’s abdominal cavity, he grew up and pupated, his pupal case peeking out between his host’s abdominal plates. When he was ready, he wiggled out from both his pupal case and his host simultaneously. He stretched his wings and set off to find a mate; which is where we first met him.

Flying upwind, following pheromones, he catches sight of his darling’s head protruding from her host. Swiftly, he flies down to her and, like his father before him, pierces her just below her head. He departs as swiftly as he appeared, his job done. Soon, his Love will be consumed by her own brood and his own little larvae will escape their original host by crawling out of the brood chamber opening in her protruding head. He will never meet them; his fleeting moment of passion with their mother was his last act before death.



Although their life cycle remains the most intriguing thing about strepsipterans, that is not where the absurdities end. This order is an enigma to taxonomists. Originally, they were thought to be closely related to beetles (due in part to their extremely reduced and modified front wings), but recent genetic work indicates they may be closer to flies, or even a relative to the larger group that includes flies and butterflies/moths.

Additionally, strepsipterans do not have the compound eyes you find in a majority of insects. Instead, they have clustered (but separate) eyelets that each produce an image of their own. These eyelets are what give the strepsipteran eyes their unique “boysenberry-like” appearance.

The BioSCAN team has recently found representatives of the order Strepsiptera (the “Twisted Wing Parasites”) from samples in both Silverlake and Mid-Wilshire neighborhoods. Adult males are extremely rare, and we were excited to share this order’s exciting and unique life story with you.

For pictures and videos of these amazing creatures, please see a recent article from Wired Science showcasing their amazing biology: http://www.wired.com/wiredscience/2014/03/parasitic-junk-trunk

Bloodsucking Flies Terrorize Pigeons in Gardena

Photograph of dorsal, lateral and ventral views of Pseudolynchia canariensis.

Pseudolynchia canariensis. Photo: Kelsey Bailey.

This week, the BIOSCAN team brings you… a squashed fly from Gardena?! This may be what it looks like but we are excited to share with you our first specimen from the fly family Hippoboscidae, commonly referred to as louse flies. This particular species, Pseudolynchia canariensis, is a parasite on pigeons and doves, a bird louse fly. The BioSCAN team was thrilled to see this specimen appear in one of the site samples, not only because these flies are relatively rare, but because many flies in this family are flightless, and some are without wings at all. Obviously, wingless species are unlikely to be caught in a Malaise trap designed for flying insects, so we were lucky to catch this flying species.

The unusual appearance of this fly tells us a lot about its life history. The flattened body (yes, it’s supposed to be that way, it hasn’t been squashed) allows the fly to slip between the feathers on its host, while keeping a low profile. Anyone that has been hiking locally may have dealt with ticks on their own body or that of a companion animal — ticks use that same flattened body shape to make themselves harder to remove. A flattened body shape (scientists refer to this as being dorso-ventrally flattened) helps prevent a parasite, in this case a fly, from being dislodged while it utilizes its food source — host blood. Feeding on the blood of another animal can be tricky business. Our BioSCAN scientists speculated that this fact (coupled with fly “old age”) may have contributed to this specimen’s tattered wings; perhaps the host tried to dislodge the feeding parasite and damaged it.

One look at the view from below and it becomes clear that the sclerotized proboscis (fancy entomology words for “tough mouthpart”) is undoubtedly painful; we don’t blame the bird for trying to get rid of it! Unfortunately for the pigeons, getting rid of these flies is not as easy as simply brushing them off. If you notice, the flies have long, curved claws on their feet. The last segments of insect legs are called the tarsi, and those claws are called tarsal claws. On most insects, these claws are small innocuous hooks — used for clinging to normal substrates. In these parasitic hippoboscids, however, these claws are enlarged with a pronounced curve to allow the fly to cling to its host — ouch!

So where did these flies come from? Originally, this species was found in the Old World tropics and subtropics, but today they have spread virtually worldwide on domestic pigeons and doves. Despite this wide range, we rarely see them — they spend most of their time flying around attached to their avian hosts. So rest assured, for as ominous as this bloodsucking fly may seem, they are solely interested in bird blood, not yours.

Second Species of Ant Decapitating Fly Found in Glendale!

For those of you who missed Lila’s exciting account of the moment Dr. Brian Brown first spotted an ant decapitating fly in one of our BioSCAN samples as it was being sorted in front of our visitors in the Nature Lab, please enjoy this post.  As Lila so eloquently described, ant decapitating flies are tiny but mighty little phorid flies that lay their eggs inside of the bodies of, you guessed it, ants.  Many of these specialized flies have been the focus of our Entomology Department’s research as conducted in other, more tropical locales, so it may come as a surprise to hear that we have these incredible phorids right here in LA.  These parasitoids (a term we use to describe organisms that eventually consume and kill their host) will not just lay an egg in any ant they come across, but instead target a particular species.


Pseudacteon californiensis. Photo credit: Kelsey Bailey

Pseudacteon californiensis. Photo credit: Kelsey Bailey

For instance, Pseudacteon californiensis, the first ant decapitator to turn up from one of our two BioSCAN sites in Glendale, preferentially seeks out the native velvety tree ant, small ants with an orange thorax that nest beneath bark and in tree cavities.  Some ant decapitating flies, like zombie hunters, “aim for the head,” but P. californiensis has been observed hovering over the abdomens of velvety tree ant workers where they appear to “lift” the abdominal segments to insert an egg into the host.  The larvae must then travel towards the head, making their way through the occipital foramen (the very narrow opening containing the connective tissue between the thorax and head), to complete their development in the head capsule, which eventually is separated from the body by enzymes released by the developing maggot.

Pseudacteon amuletum. Photo credit: Phyllis Sun

Pseudacteon amuletum. Photo credit: Phyllis Sun

Our second Pseudacteon discovery from the same site in Glendale is P. amuletum, named from the Latin word for amulet due to its distinct horseshoe shaped oviscape that is reminiscent of a charm or pendant. One may also infer a deeper meaning of the name beyond shape but also of function: amulets can protect, and this species of Pseudacteon is important as a form of biological control against fire ants.  A close relative of P. amuletum has been used to help control the spread of the imported fire ant Solenopsis invicta due in part for its rate of parasitism, but mainly because of how it affects the ant’s behavior. Solenopsis ants assume a very strange position when they detect Pseudacteon flies by lifting up their bodies and tucking their abdomens under and forward into a “C” shape with the same incredible skill of a Cirque de Soleil contortionist. It is believed that this helps protect the abdomen from egg invasion, but the trade-off is reduced foraging by the ant, which puts it at a disadvantage in relation to other more industrious, less preoccupied ant species. In this way, Pseudacteon contributes to a reduced fire ant population, which is greatly appreciated by those who know the alarming pain of a fire ant sting. 

Although Pseudacteon have been recorded from LA before, they have become increasingly rare as their native ant hosts are pushed out by the ubiquitous Argentine ant, an introduced species that thrives in altered urban habitats, is not a picky eater, and succeeds by teaming up with sister ants from other colonies, joining forces against native ant species.  Knowing that the presence of these flies indicates a healthy population of 2 species of native ants makes this current find from one of our BioSCAN sites very impressive!


Botfly Found in Los Feliz

Much to the BioSCAN team’s excitement, we collected our first specimen of a large bodied fly that is infamous for its bizarre life history. Botflies are a group of flies in the Family Oestridae that are obligate parasites on mammals; the only way for their larvae to develop is to feed inside the bodies of their host.

For those of you that have heard of botflies before, you might be familiar with horrifying tales of people who have traveled to the tropics and have been infested with a maggot (or multiple maggots!) that can reach an inch in length when fully grown.  That particular botfly, Dermatobia hominis, has been dubbed the “human botfly” for infecting humans, including one Entomology staff member, but in truth the fly does not target human beings (which would be foolish considering our strong ability to remove parasites from our skin)  nor does it really choose a particular host at all! Rather, the female botfly of this species attaches an egg to the underside of a mosquito’s abdomen in hopes that the mosquito will find a warm mammal to feed on — a cow, deer, or the occasional human being — so that the larva can emerge from the egg and bore into the skin where it will develop.

Photo credit: Kelsey Bailey

Photo credit: Kelsey Bailey

But there is no need to panic: the botfly found at one of the BioSCAN sites in Los Feliz is the California rodent botfly Cuterebra latifrons, which specializes in parasitizing the Dusky-footed wood rat, Neotoma fuscipes. This large, exquisite fly, with its white tufts of hair and shiny black and white Rorschach  patterned face, is not harmful to humans, but is certainly a wood rat’s nightmare. Females lay their eggs in the wood rats nests which hatch upon stimulation from movement and heat given off from the rat’s body.  The larvae then develop in the skin of the rat, which can have devastating effects to an individual rat if infested in high enough numbers.

In contrast,  some species of botfly are ingested as their hosts groom themselves and develop inside the digestive track, and others, like the “snot bots” (one of my personal favorite nicknames for any group of flies), hover around the nostrils of their host, take aim, and shoot live larvae right up the nose!  We should appreciate that our California rodent botfly is a little more refined.

Scoliid Wasp Seeks Scarab


Photo credit: Phyllis Sun

As much as I am an ardent enthusiast for the microscopic, mostly unseen insects that make up the vast majority of what we collect in our Malaise traps (most are only a few millimeters in size!), I can not help but become awestruck by specimens that are as large as these wasps that were collected from our Nature Garden. Scoliid wasps can reach up to 6 centimeters, a relatively large size for an insect that becomes even more noticeable when you see them land on a flower in search of nectar, the stem bowing under their weight as they feed. I had the pleasure of observing them feeding one nice warm day last year, a wonderful reminder that insect pollinators come in many varieties beyond bees and butterflies (see the recent article in the journal Science: Garibaldi, L. A., et al. 2013. Wild pollinators enhance fruit set of crops regardless of honey bee abundance. Science [published online 28 Feb 2013]. doi:10.1126/science.1230200 ).

But, as much as watching these giant solitary wasps feed on flowers was a delight, the real joy would be to see them in action as they hunt for beetles. Female scoliid wasps, like so many insects, are hard-working mothers that must find the proper food source for their young larvae, which have very different nutritional requirements. Scoliid larvae are predatory on beetle larvae (commonly called “grubs”), mainly beetles in the family Scarabaeidae, which live deep under the soil. Female scoliid wasps fly low to the ground to enable them to detect a single beetle larva, and when found, will incredibly start to dig into the soil, first with their mandibles and then with their legs, until they reach the big juicy beetle grub. The female then stings the immature beetle, paralyzing it temporarily so that she can lay one single egg on its underside. The beetle grub will eventually wake up and continue to feed on roots underground, until it succumbs to being eaten externally by the wasp larva.


Photo credit: Phyllis Sun

This scoliid stunner from our sample is identified as Campsomeris tolteca, one of 20 species that are recognized in North America. The females can be differentiated from the males by having shorter antennae, larger abdomens and 6 abdominal segments (males have 7).  Scoliids have characteristic wrinkled wing edges and are mostly black with yellow, white, or red accents, with color patterns that vary between the sexes.  LA city dwellers have reported seeing them flying low over their compost piles, a perfect home for scarab grubs, but hopefully there will soon be sightings of scoliids seeking scarabs in the Museum’s Nature Garden.

Fungus feeding, “flat-footed” flies


Grossoseta pacifica. Photo credit: Inna-Marie Strazhnik

Few might suspect that Los Angeles, a city of millions of people, is a hotbed of the dowdy-sounding “flat-footed flies” in the family Platypezidae. Compared to  eastern Northern America, where these flies are relatively rarely encountered, backyards in L.A. have at least 3 species of these strange flies. In the past few months alone, individuals in the species Grossoseta pacifica (shown above) and Protoclythia californica have been collected from the Museum’s Nature Garden and a backyard site.

The flat-footed flies were given this odd moniker from the flattened hind tarsi, the segments that make up the “foot” on the hind legs, in most females and some males. It  has been suggested that the flattened segments for flies in this group may be an adaptation for spreading the spores of host-specific mushrooms, as females will insert eggs into the gills or pores of living mushrooms where the larvae will feed.


Calostarsa insignis. Photo credit: Brian Brown

Extraordinary examples of this can be seen in the males within the genus Calostarsa,  which have elaborately ornamented projections on their hind legs that males presumably use to flag down female flies. Male flat-footed flies form large aerial mating swarms and will “dance” with their legs held down, displaying their tarsal accoutrements. In another genus, Microsania, males are attracted to smoke plumes where the swarm will congregate, a behavior that is a mystery to entomologists, proving that there is still much to be learned about these intriguing flies.

References: Kessel, E.L. (1963) The genus Calotarsa, with special reference to C. insignis Aldrich (Diptera: Platypezidae). Occasional Papers of the California Academy of Sciences 39: 1–24.