Urban phorid flies in Los Angeles, California, USA

Last week Emily Hartop and I published a new paper on the phorid fly fauna of Los Angeles, in the journal Urban Ecosytems (get the full text here). This is the culmination of years of work by all of the BioSCAN team, in getting the project up and running, sorting and identifying 40,000+ flies (mostly Megaselia, mostly the work of Emily), and looking for patterns in the community.

Lisa Gonzalez of the BioSCAN project and Joe Hogg, one of the site hosts, in Joe's backyard.

Lisa Gonzalez of the BioSCAN project and Joe Hogg, one of the site hosts, in Joe’s backyard.

The major findings for us is that the Los Angeles urban fauna consists of about 100 species (43 of which were new to science and described by us for the first time), but individual sites (mostly backyards) had from the mid-twenties in the area just west of the museum to 83 species in Glendale, right up against the mountains.

The commonest species by far is Megaselia agarici, a fungus-feeding species possibly introduced from elsewhere. It is sometimes a pest in commercial mushroom farms, but here they are extremely common in “wild” Agaricus mushrooms that we have found in the city and brought indoors for rearing the flies. This species is so prevalent, that it was found in every one of our 30 sites (as were a few other species), and in some sites it made up over 70% of the phorids captured. Many of the other commonest species in the study were also mushroom feeders, such that at least 40% of our collected phorids have this lifestyle.

Thirty sites of the phase I BioSCAN project in Los Angeles

Thirty sites of the phase I BioSCAN project in Los Angeles

In contrast, our most diverse site had many more species that do other things, especially those that parasitize ants (including the infamous “ant-decapitating flies” I have written about elsewhere). These ant-associated species are completely absent from the downtown area, almost certainly because the introduced Argentine ants have completely eradicated the other species of ants formerly found here. It is difficult to know how much damage was caused by the introduction of “argies” here, but it was a catastrophe for phorid flies.

Many other results are in the paper, and I urge all interested fly aficionados to read it. The next step will be to associate these diversity data with variables of climate and urbanization to see if we can find some correlations that make sense. We are far from finished working on L.A. phorids! But the outstanding remaining question about this phorid community we have here is whether it is representative of other urban phorid assemblages, here in California, here in North America, and throughout the world. Are all urban sites dominated by fungivores? Do they all have a superdominant species like M. agarici (or maybe even M. agarici itself)? We just don’t have any data to know the answers yet.

Thirty of the 43 new species of phorid flies from Los Angeles

Thirty of the 43 new species of phorid flies from Los Angeles

Additionally, one of our next studies will be to look at other groups of insects (including other families of flies) to see how they are distributed in the city. I expect that there will be some major differences among groups, attributable to small-scale differences among sites. One study (Avondet et al. 2003) in Ohio, looked at, among other things, the distribution of dumpsters to help predict the diversity of Drosophlia “fruit flies” (Drosophilidae, better referred to as vinegar flies or pomace flies) in the urban landscape! Probably the diversity of plants, flowers, amount of hardscape vs yard, mulch versus grass, and so on will greatly affect the number of species at a site, but our ability to predict this is still in the infancy stage. Stay tuned for more…

Cited article:
J.L. Avondet, R.B. Blair, D.J. Berg, and M.A. Ebbert. 2003. Drosophila (Diptera: Drosophilidae) response to changes in ecological parameters across an urban gradient. Environmental Entomology 32(2): 347- 358.

The white-tailed phorid, Megaselia albicaudata

It is amazing to me that some phorid flies are found in multiple environments around the world. Less surprising are the scavengers that live mostly in human-built structures or that need scraps of our civilization to thrive. Usually, these scavengers are well-known to us, through their large numbers and occasional nuisance status. But what about the”white-tailed phorid” (I just made that name up, based on the Latin name!), an obscure but seemingly ubiquitous fly?albicaudlatsmall

There is no question that this 1.5 mm long fly is well-named: the male genitalia are a shocking white in comparison to the rest of the rather dingy brown body. It was described in 1910 from England, and is well-known from other parts of the world such as Finland, Israel, and China. It is also found in the two big fly inventories that I am part of: the Los Angeles County Natural History Museum’s urban biodiversity project called “BioSCAN” and the Costa Rican “ZADBI” project in a tropical cloud forest.

How can a species live in such disparate climates and habitats? Nobody knows, just as nobody knows what the larvae of this fly eat. I have looked at specimens from both North America and Costa Rica, and I am sure they are morphologically the same species, not two species masquerading as one doing different things in different places. It is one of thousands of Megaselia worldwide that we know nothing about, but discovering phorid lifestyles is part of our* phorid research effort. Obviously, we have a long way to go when such a widespread species remains a mystery.

*Note, when I say “our”, I mean the few people worldwide actively pursuing phorid research, including our group here at LACM, consisting of Emily Hartop, Lisa Gonzalez, and me.

Windows

No, not the operating system. I’m talking about physical windows in a building. If some doors, other windows, or even the whole side of the building are open, windows can be fantastic places to collect flies. Like most dipterists, I go right to the windows of any building I am in, to see what is there. Sometimes, people look at me as if I am crazy, but I forgive them because they just don’t realize how cool flies are yet (top to bottom, a ropalomerid, stratiomyid, and tababid).

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

Wendy Porras and I just got back from La Selva Biological Station in Costa Rica, where half of the dining room is wide open, while the other half has screened windows throughout. We found a lot of extremely photogenic flies, some of which I show here. We put them in a more pleasing background than screening, wrangled them to sit still, and got the shots we wanted. A little honey on the leaves helped, as some flies were apparently hungry after several hours of banging their heads against metal cables.

Forty-five seconds of fly swarming

One of my favorite museum exhibits is the round ceiling tank at the Monterey Bay aquarium, where a huge school of silver-colored fish swim in an endless circle. It is hypnotic, fascinating, and strangely calming.

Watching flies in a mating swarm can be that way too. Usually, it is a group of male flies we see, all jockeying for the best position in the air. Presumably, this allows arriving females to recognize those that are superior and choose the male in the “best” position for the one with which they will mate.

Thinking of the Monterey Bay experience, I wanted to document a fly mating swarm, and finally got the chance this summer. A group of empid flies (also known as “dance flies”) were flying in a brilliant shaft of light against a dark conifer background, perfect for my purposes. Let me know what you think of the result!

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Diptera Blitz wrap-up

EOL micropezidOf course, our event was a tremendous success. Some highlights:

– bat-netting by Carl Dick got us streblid records, bird-netting by Kimball Garrett got some hippoboscids.

– Carlos de la Rosa (the Director of the La Selva Biological Station) joined the team, working on chironomid midge pupal exuviae

– Michael Turelli, professor of genetics at UC Davis and (at least on this trip) amateur drosophilid collector gave a stunning talk about using the intracellular bacterium Wohlbachia to eliminate dengue

– the final event, a barbeque, featured a short film about the week by LACM videographer Edgar Chamorro.

Some photos follow, including a group photo of nearly all participants. These photos help portray not only the enjoyment, but also the dedication of the team to document as many Zurqui flies as possible. The results of their efforts will appear soon on this website.

group
Yes, nearly all these people came to Costa Rica to study flies! (click photo for larger view)

Diptera blitz kimball
LACM ornithologist Kimball Garrett releasing a bird after checking it for hippoboscids (bird louse flies)

Manuel Art Brian
Manuel Zumbado, Brian Brown, Art Borkent: three dipterological amigos

A monster in the garden

bumble-bee-asilidThere is a voracious predator in our nature garden at the Natural History Museum of Los Angeles County; luckily it is only about an inch long. It is a “bumble bee robber fly” of the genus Mallophora. It is hanging out on the kangaroo paws in the garden on the east side of the building. It picks off wasps and bees, injects them with venom and digestive enzymes, and sucks them dry. As I said, we can all be thankful that it is only an inch long, but it is beautiful and fun to watch!

New flies in town

asteiid drawer

asteiid drawer

The “new” collection of flies from Utah State University has arrived, and what a collection it is! The number of specimens and some of the cool species among the material surpasses my wildest dreams. Of course, we gave up a great collection to obtain this material, as documented in my previous blog (“Fly Specialization at the LACM”), but these new Diptera holdings are mesmerizing to me.

For example, in an earlier blog I wrote about finding the unusual family Asteiidae here on the Museum grounds. The supply was only our second specimens in the entire collection, yet look at the holdings from Utah State University! Half the tightly packed drawer of them-I guess they are not so rare after all.

tons of tachinids

tons of tachinids

More superlatives: seven drawers jammed with unsorted fungus gnats. Lots of tachinids (parasitic flies): about 40 unsorted drawers of them!

There was even a family new to our collection- the southeast Asian Nothybiidae. They look like a school of minnows heading upstream in the unit tray.

school of nothybiids

school of nothybiids

That’s the thing about this collection: most of it is unsorted and therefore full of potential for new species. As an example, amongst the phorids was the first-ever specimen of the genus Cyrtophorina from Central America, a new species of the previously well-known genus Anevrina from Mexico, and a few things that are just weird and unidentifiable to me at this time.

To be sure, this is a collection that only a dipterist would love (and some people I show these photos to shudder in dismay), but part of the incentive for doing this exchange was to stimulate interest in the LACM fly holdings. Hopefully, this brief report will help do so,

How to get rid of flies, part 1

This must be the most frequently asked question about flies, and although it is not really my field, I feel compelled to comment on it. After all, as much as we appreciate and admire our two-winged friends, they can be annoying to downright deadly at times. So, for those suffering from from an affliction of Diptera, here is a tentative key to fly problems I have faced.

NOTE 1: An “affliction” is more than the odd fly or two. Most fly problems are avoided by the commonsense practices of using screens on windows and keeping trash outdoors.

NOTE 2: My advice is for entertainment purposes only; I do not pretend to be an expert on fly control and I cannot respond for requests to help with fly problems. Please contact a licensed pest control professional.

Key to Fly Problems:

1. The fly problem is indoors… go to lead 2
-. The fly problem is outdoors… will be in part 2 (next blog)

2. Big grey, grey and black striped flies, or metallic blue or green flies suddenly appear in large numbers, usually attracted to the daylight at windows… Answer: 1) Something has died in or under your home (frequently a rat). Look for and dispose of carcasses. Be aware that this problem will go away in a week or two as the flies go through the food. 2) If this occurs in early spring or on warm winter days (where winters are cold), it is more likely these are overwintering cluster flies that have been “awakened” by warm temperatures. You need to seal around window casings (the usual entry point) to prevent them from entering the house.

– Smaller, less chunky flies… 3

3. Hairy, mothlike flies with broad but pointed wings (see photo below)… Answer: You have flies called moth or drain flies. Their larvae live in the accumulated sludge in your drains. Clean the drains and they should go away.

– Flies not so hairy and wings not pointed… 4

4. Small yellowish flies slowly hovering hovering over fruit, wine glasses, or open trash… Answer: Pomace or vinegar flies (genus Drosophila), also commonly known as “fruit flies”. Attracted to odors of decay, especially fermentation. Get rid of the decaying material, clean up trash, and the flies will quickly go away.

– Flies not yellow, or if yellow, run quickly and do not slowly hover… 5

5. A group of flies forming a swarm (a group of flying individuals), gently zig-zagging, always in flight in doorways, alcoves, or the center of a room… Answer: Lesser house fly males have come in through an open door or window. They are harmless and will disappear in a few hours. Window and door screens will prevent this.

– Not forming a swarm indoors… 6

6. Black-winged, tiny gnats that seem to be attracted to lights, or strangely, to the pages of a book you are reading at night. They seem to gently fly or “dance” against the pages or whatever surface. Associated with house plants… Answer: Dark-winged fungus gnats are breeding in the soil of your house plants. They are harmless, but potentially annoying. If they become unbearable, try watering the plants less, or getting rid of the most affected plant.

– Flies not dark winged, not a gentle fliers, not associated with plants… 8

8. Flies usually run, not fly, in a distinctive “stop-go” pattern. When they fly, the flight is direct, not slowly hovering. Color various, but often with yellow… Answer: Phorid flies are in your house. Either something has died in the walls, where the bigger blow flies cannot get to it, you have a sewage leak under your house, or some other situation is amiss. Call in the professionals if they are overwhelming.

– Anything that gets to here is in the category of less common “pests” that need to be diagnosed on an individual basis. Different flies affect the indoors in a variety of ways in other parts of the world. I would be happy to read any accounts that differ from what I have written here.

next blog: outdoor fly pests

Fly specialization at the LACM

We are doing something a little daring, but certainly exciting here at the Natural History Museum of Los Angeles County. We have decided to specialize on flies.

drawer-of-flies drawer of unsorted flies from the LACM collection

Why would we do this (besides because we are obsessed)? Most insect collections are comprehensive, trying to house as big a variety of all groups as possible. Basically, we want to to become one of the best Diptera collections in the country, or even the world. You can’t do that unless you are ready to give up something else. For us, it is future growth in non-target groups, like butterflies and beetles. We’ll take care of what we have, but we are not accepting any more.

An even more radical version of the specialization involves exchanging away non-Diptera parts of the collection. To do this, you need to find other like-minded institutions that wish to grow in a similar way. In our case, we found a first partner in the Utah State University, especially with Dr. James Pitts. There, Dr. Wilford Hansen has built an excellent collection of mostly Neotropical Diptera. The current staff of their entomology department, however, is more interested in Hymenoptera, and this spring we are doing a large-scale exchange of USU Diptera for LACM Hymenoptera (exclusive of ants and bees).

This exchange includes about 600 drawers of material on each side. It more than doubles our holdings of general Diptera, not including our already major collections of Phoridae, Blephariceridae, and Neotropical Psychodidae. It also makes USU a major Hymenoptera collection, a truly win-win arrangement.

Exchanges can quickly change the face of the collection, but they are expensive. Moving 600 drawers to Logan, Utah, and bringing same number back to Los Angeles will cost about $4000 and lots of staff time. Still, this is much less money than that required to build a 600 drawer collection from scratch, and we are thrilled by it.

I foresee the possibility of more such exchanges in the future for the LACM, and welcome inquiries from curators who feel that such an arrangement would benefit their collections as well.

Peacock fly

This is a message to my from my friend, biologist Lynn Faust:

Just for fun, am sending you this photo of a cool little fly that put on quite a show for me last May near (not in) the traps in the Smokies. He landed on the roof of my car and proceeding to fan his wings like a peacock and slowly turn and preen. Every time I scared him off with my camera, he circled and returned and spread his wings again. This went on for 30 minutes until I finally needed to leave. I never saw another fly (female) so it was as if he(?) was displaying for me. Of course I did not know what type of fly he was at the time, but just on a guess, googled “peacock fly” and found very similar photos in the Tephritidae family. So, I am asking nothing, just sharing this fun photo since you love flies. Sorry it is not a phorid! Lynn Faust

peacock-fly

Actually, it is a ulidiid, not a tephritid, and a very entertaining one! Thanks, Lynn.