Tag Archives: Diptera

Problems photographing flies. 3. You need light.

Okay, based on parts 1 and 2 of this series, you want to use high apertures (lens f-stop settings) to get lots in focus, but you need to use intermediate apertures to avoid diffraction blurriness. Either you have to focus stack (often impractical in the field) or accept a compromise f-stop like f11. So how does f11 work for you?

In all but the brightest light, f11 (or f8) will require long exposure times, giving ample opportunity for you or the fly to move, blurring the exposure. We’re back to either needing a motionless fly (unlikely) or, this time, more light.

Wait, can’t you just dial up the ISO (sensor sensitivity) on your new digital camera so you can use a faster shutter speed? Yes, but you increase the digital graininess (“noise”) in the photo, such that resolution at high magnifications is destroyed.

Here are a series of closeups of bristles on a tachinid fly showing this effect:

ISO 100

ISO 200

ISO 400

ISO 800

ISO 1000

ISO 1600

ISO 6400

This series of shots tells me that, for my camera, ISO 200 is about the same as 100. For ISO 400-800 I get some degradation, but it is still pretty good. Above ISO 800, thing get pretty mushy. You need to check this in your camera, too.

The result is that changing ISO only helps me a little. If I want the highest quality images, I need more light. How to get this light is my next topic.

Why so spiny?

Acontistoptera female
I got a lot of questions about why yesterday’s fly would be so spiny. I can think of two plausible answers, both of which might be right.

Firstly, such spiny flies are almost invariably found in species associated with ants, especially army ants. As evidence for this, here are 3 flies from the New World tropics found with Labidus army ants: Acontistoptera, in which the long setae (bristles) are found almost only on the wing rudiments, Adelopteromyia, which are spiny on the wing and on the body (especially the head), and Xanionotum, which has multiple rows transversely across the abdomen.
Adelopteromyia female
The large setae could be used to fend off attacking ants, like a porcupine, or for sensory purposes in the darkness of underground ant colonies. Or both. One thing to keep in mind is that the flies probably can move the setae, erecting them or laying them down. They are much more flexible, mobile, and speedy than you might think, as they literally runs circles around the host ants.
Xanionotum female

A brief respite from photography posts: another bizarre phorid

My friend in New Zealand, Hugh Oliver, saw the picture of the wingless female phorid in my last blog post, and asked for more photos of weird phorids. I didn’t even know he was looking at my blog, but just for him I am posting this photo of an extremely bizarre specimen we found just this week in material from Thailand. I think it is a female of the genus Rhynchomicropteron, but if so, it is an extremely unusual one! Thanks to Lisa Gonzalez for pointing it out to me, and Inna-Marie Strazhnik for photographing it. Maybe it can be number 16 in Terry Wheeler’s posts about why flies are great.

female Rhynchomicropteron?

Problems photographing flies. 1. Of what is your camera capable?

A tachinid fly - looks good, right?

Flies are fantastic subjects for photography, but they present many challenges because they are

1. small,

2.active,

3. often metallic and bristly.

All of these are factors that cause problems that I’ll discuss in the next few postings.

[The reason I’m writing about this is that there is so little good macrophotography information about insects like flies. I assume interested readers know the basics of 35 mm digital photography. If this subject doesn’t grab you, go back and re-read the last post by Lisa Gonzalez, which was a real crowd-pleaser]

When you photograph small things at high magnification, your depth of field is frighteningly shallow. Take a shot at f 1.4 and you’ll get maybe one tarsomere and a wingtip in focus. The rest will be a blur. Therefore, you need  to close down to f 22 or f 32 to get everything in focus- correct? Unfortunately, when you do this, you start to distort the image through diffraction. It’s not really a problem when photographing big things (like landscapes), but flies are 1. small.

Above is a good-sized tachinid fly. I photographed it with my camera (Nikon D-7000) on a tripod, using a 125 mm macro lens set at f 22. At this magnification it looks pretty sharp, but look closer (below). You’ll softness from diffraction that no fly obsessed photographer (and I hope you are one) would tolerate. And since most flies are smaller than this tachinid, what we see in this magnified view is ALL we’ll get.

f 22 -blech!

At the next setting, f 16, sharpness is definitely better. Scroll down to see other settings.

f 16, a little better

f 11, better yet

f8 - sharp

f 5.6 - who knew?

The problem, of course, is that by f 5.6 the legs are all out of focus. You have to pick a compromise (f 11 works for me) or do something else, photostacking, which only works well with stationary objects (and remember, flies are 2. active). More compromises are ahead.

To get the best results, you first need to know what your camera can do. Everyone needs to test their camera and lenses this way to see what is possible. Then you can move on too what is practical.

Next- how do you get to use that f 11 setting?

Keep your eyes on the flies

[This is a guest post by Lisa Gonzalez, one of my field team members.]

Lisa Gonzalez in demonstration mode

Lisa Gonzalez in demonstration mode

Last week I had the incredible honor of joining a small team that included Wendy, a parataxonomist; Inna, a scientific illustrator and videographer; and Kat, an accomplished amateur photographer; under the guidance of the respected Dipterist Dr. Brian Brown, to the lush lowland tropics of Costa Rica on a phorid fly foraging expedition. Our goal was to record and observe parasitic phorid fly behavior– in particular to begin unraveling the mysteries surrounding certain phorid flies in the genera Apocephalus and Dohrniphora— as well as collecting any specimens that struck our interest.

My first trip to this beautiful, magical country was 10 years ago, but every day that has gone by since has been a day that I have anticipated returning. So suffice it to say I was beyond excited at the prospect of spending entire days under the forest canopy, scanning the ground and leaves for parasitic phorids and their specific hosts.

People who know me know that my passion for insects runs deep, but I still get an occasional incredulous glance, a slightly furrowed brow or a polite smile and shrug from my non-entomologist friends as I explain that the vast majority of our trip will be dedicated to looking for 3 mm sized flies (even though they know it is part of a scientific project, as in, WORK.) No zip lines, no sipping mango margaritas on the beach –sugar on the rim, hold the salt!– no waiting for a quetzal to fly by for that perfect photo op.

No, my friends, we will be looking for flies, cool parasitic ones, because they are out there, lurking in the jungle, waiting for someone to observe them doing things that are infinitely more fascinating to me than the showiest toucan or the noisiest oropendola. Somebody needs to give them the attention they deserve!

After a morning cup of that fine, fine Costa Rican coffee, we used the help of the phorid flies themselves, namely their incredible ability to detect the alarm pheromones of their hosts. We searched the tree trunks and undergrowth for the specific types of ants that serve as the hosts (Odontomachus sp. and Paraponera clavata in this case) so that we could collect them, crush them, and thus attract the flies we so anxiously sought, a technique that Brian serendipitously but no less ingeniously discovered 20 years ago.

As the flies started to hone in on the chemicals released by the distressed ants, I felt myself becoming completely entranced by the miniature drama unfolding at my feet. This is the point where I struggle to find my mental middle zone, maintaining a focus on the flies while not becoming too tunnel-visioned; still being aware of my surroundings since, after all, we are in a jungle with stinging ants and wasps everywhere, and an occasional venomous snake, but most importantly, not wanting to miss any phorid action on the sidelines.

Keeping your eyes on the flies and not being distracted by bedazzling morphos or adorable sloths (my goodness, they ARE cute!) reaps great rewards for anyone with even a modest interest in animal biology and biodiversity. For an entomologist, or those willing to scale down their perspective and peer into the microcosmos, it is a truly awesome experience to see a minute female fly risk her own life by attacking an ant at least twice her size, desperately needing a place to lay her egg (or eggs), using a variety of bodily tools, such as ovipositors shaped like sabers or mouthparts serrated like knives. These females are so alert and nimble, like little ninjas, and although the outcome of their efforts, which results in decapitation or an “‘Alien’ chest burster” style host death depending on the phorid species, may seem cruel to our human sensibilities, I see a brave and resilient mother struggling to care for her young (that’s a whole lot of anthropormorphism for one sentence, I know!)

Brian decided to expand our efforts in the field on this trip by collecting female phorids and hosts and observing them in captivity in our make shift lab. He very generously put me in charge of this part of the project, proclaiming that I am “good at keeping bugs alive” from my years spent as the museum’s insect zoo technician, a professional extension of the top secret insectary I kept in my closet when I still lived with my parents many years ago. After several days of working out humidity issues, adding extra masking tape for the sneaky escape artists, and trying to provide a stress free environment for the flies to “go about their business,” we were able to observe some provocative behavior in captivity. Some preliminary work was done with the species Dohrniphora conlanorum, and we successfully reared larvae of Apocephalus paraponerae. I was alone in the lab when I first spied the chubby little bundles of maggot-y joy in the abdominal cavity of the Paraponera ants, and in my solitude was able to get up and do my celebratory maggot dance without shame. The pure excitement over seeing a world that most people rarely stop to notice, the thrill of something new on the other end of your scope, is greater than a million zip line adrenaline rushes or brain-in-a-jacuzzi delicious tropical rum buzzes to me. I am so elated to have been a part of this project, and I hope you enjoyed my attempt to briefly describe that elation. Now to start counting the days until I return once more…

Army ant raid of my dreams

I suppose most people have anxiety dreams, in which things are going horribly wrong because, in their dreams, they are late, lost, without something vital, or otherwise unable to figure out what’s going on. Being an entomological geek, and obsessed with field work, my anxiety dreams are often centered around being in a great tropical place, surrounded by social insects like ants and bees, but not having collecting equipment, having to leave, rain starting, and so on. I wake up frustrated, hoping that next time I’m in the tropics none of these things happened to me.

A couple of days ago, we pulled off the road in an area known to the locals as “Bambu de Suerre” and walked on a short rocky path into the forest. We were collecting for a while at a nest of Pheidole ants, when I decided to walk further up the trail. I started to hear the sound of the distinctive ant birds that follow army ant raids, and sure enough came across a massive raid of Labidus praedator.

Associated with these ants was a huge assortment of flies, in incredible numbers. Clouds of tachinids and conopids (Stylogaster) were buzzing around the undergrowth, while closer inspection showed that there were equivalent masses of phorid flies a few millimeters above the ground, attacking the ants. We were collecting 5 or 6 flies per aspirator attempt without even looking, just waving her aspirator is blindly around the ants and sucking in air. We collected hundreds of flies, truly an amazing event, and one I have rarely been lucky enough to stumble upon.

a small part of our fly catch

The flies included several species of Apocephalus ant decapitating flies, with the most common being A. praedator. As well, we collected some highly host-specific phorid genera like Cremersia that are associated strictly with non-Eciton army ants. One of the amazing things about Cremersia is that their ovipositors are complicated and asymmetrical. We don’t know how they use them, but they are so unusual that the females were originally described as males!

female Cremersia

Today is our last field day for this trip. There is still time for another dream to come true.

In Costa Rica with bloodsuckers

Being in the field, it is hard to ignore the biting flies. Mosquitoes, black flies, horse flies, sand flies, and no-see-ums all make their mark. Sometimes I forget, however, that humans are not the only recipients of their unwanted attention. For example, my good friend Dr. Art Borkent studies a group of flies called the Corethrellidae, whose mosquito-like females feed on frogs and are attracted to frog calls. But Art’s main study group are the aforementioned no-see-ums, technically known as Ceratopogonidae. The many species of these minute flies have differing ways of life, as some are predators of other insects, some are misery inducing biters of vertebrates (especially on beaches, where they can clear the humans out during certain times of day), and surprisingly, some feed on the “blood” (haemolymph) of other insects.

We saw a spectacular example of this yesterday here in Costa Rica. We took a day trip to a spot called Las Minas, where we were looking (mostly unsuccessfully) for different ant-decapitating flies. While searching around, Wendy Porras, our Costa Rican colleague, found a katydid with something strange on it. Being an excellent field biologist, Wendy immediately recognized that this white, almost pea-sized attachment to the katydid’s abdomen was a swollen female ceratopogonid, full of eggs.

ceratopogonid on katydid's back

I hope Art will forgive me, but I didn’t collect the specimen. I got distracted by other things, and by the time I thought of it, the fly had already left. This is a case of bad field work on my part. Certainly when significantly unusual things are seen, they should be collected so that the specimens accompany the life history observations. Hopefully we can make up for it with even more significant observations on the phorid flies that we came here to study.

closeup of the fly

[Thanks to A. Borkent for a couple of corrections to the original post]

In Costa Rica, II

We have had quite a bit of rain so far, nothing you wouldn’t expect in a rain forest, but it makes collecting an episodic affair. The light traps run every night, however, even in the pounding rain. So far (after one night), they have turned up two interesting flies.

The first is an acalyptrate, perhaps a lauxaniid, with interesting lines of color along the wing veins. I don’t know how unusual this is, since I don’t work on lauxaniids, but I have never seen anything like this before.

bad photo of a lauxaniid in alcohol

The second interesting thing is a female bee killing fly, genus Melaloncha, from a group that I have worked extensively on. Bee killing flies are parasitoids that attack stingless bees, introduced honey bees, and bumble bees. They are found throughout the Neotropical Region, except for Chile, and attack their hosts either at flowers or at colony entrances. I worked for years on these flies, and have described many new species. In order to collect them we had to learn a lot about their natural history, the most are active only in bright sun in the warmest parts of the day. But there is also a published record from Panama of them attacking nocturnal sweat bee.

Melaloncha

Could this be one of those nocturnal bee killers? Perhaps, and this is one of the great things about using a “new” collecting technique in the tropics-finding different things even in groups you have worked on for many years.

New frontiers in Costa Rica

Tapanti NP

My late colleague, the hymenopterist Roy Snelling, used to ask me disdainfully, “why go to Costa Rica; everything is already known from there.” Even Roy knew, however, that this wasn’t true. His mistaken assertion was that so many people had collected in CR that, given the large number of other places that had not received any attention, it would be a waste of time to go back to a small Central American country.

I disagreed with his statement for many reasons. First of all, there aren’t enough dipterists on the planet to make even a tiny part of CR “overcollected.” There are so many habitats and microenvironments in a country with a mountain range down its center in the tropical zone, that doing an inventory of all of Costa Rica is probably impossible. From dry tropical forest in the northwest to the near treeline heights of the Cerro de la Muerte, and all the rain forest inbetween, CR is a biodiversity paradise.

But more interestingly, it is possible to find new frontiers in the same sites by using different collecting techniques. Last year, for some reason, we decided to try blacklight collecting in Costa Rica for the first time since my trips in the 1980s. We used a trap of my design that was so successful, I decided to write it up for publication (watch for it in Entomological News).

Using this “old” technique again, we managed to wring out some incredible specimens of Phoridae and one special sphaerocerid from a mid-elevation site from which we otherwise had no special expectations.

For phorids, our technique yielded new specimens and a new species of a genus previously known from only a couple of females from elsewhere in Costa Rica. This genus is marked by incredible huge palps with outrageously long apical setae. Additionally, we got some parasitic phorids I had never seen before, as if we had gone to an entirely new continent. Believe me, I have gone through hundreds of samples Costa Rica, and have looked at least 50,000 specimens from this country, so when I see a congregation of new things, I take notice.

the phorid with huge palps - a fuzzy photo

The sphaerocerid was the second known specimen and species of the genus Podiomitra of the incredibly rare subfamily Homalomitrinae. Although I’m not an expert on these flies, I knew as soon as I saw it that it was something special.

Podiomitra sp.

Bottom line: we have to keep trying new collecting methods, even if they are old collecting methods. I’m going back to Costa Rica at the end of February, and I’ll be bringing my lights again!

How we started working on “rare” bee-killing flies

The most beautiful phorid flies are in the genus Melaloncha, also known as bee killing flies. I have no small bias in this statement, however, since I worked on them for several years and grew to be very fond of them.

Melaloncha punctifrons, female

One of the allures of these flies was their rarity when I first started. In all of the collections I surveyed, I could find only a few specimens, about 100 in total. There were many new species among these specimens, however, so I knew that the 32 described species was only the tip of the iceberg. But how was I to uncover the rest of that iceberg?

Many parasitic phorid flies seem to be attracted to masses of their hosts. Logically, aggregations of hosts should create aggregations of parasitoids, so Giar-Ann Kung and I decided to try to make aggregations of stingless bees, the known hosts of these flies. Monty Wood, a fellow dipterist who works on tachinid flies, told me that when he sprayed a mixture of honey, Coca-Cola, and water onto undergrowth vegetation in an attempt to attract his flies often attracted huge aggregations of stingless bees instead. Therefore we tried spraying honey and water, and were almost immediately successful in attracting bees, and eventually flies. There was one other required condition, however: it had to be in the sunlight, or the flies would not be attracted. This is contrary to most phorids, which tend to be more active in shade.

Melaloncha acoma attacking stingless bee

Once we adopted the honey spray and sunlight combination, we started collecting large numbers of these flies, eventually collecting thousands of them. Sometimes, we were almost too successful in attracting the bees, producing gigantic aggregations that made it impossible to breathe or see anything, necessitating the use of jury rigged bee veils. These consisted of an insect net placed over the head and sealed around the neck with rubber bands. Eventually, though, the tiny stingless bees would get in, and we’d have to beat a retreat to get the annoying things out of our eyes, ears, and noses.

Me wearing a jury-rigged "bee veil" in Argentina, 2003

It was all worth it though, as we ended up catching 50-100 Melalonchaper day at good sites, and found almost 150 new species. I think there are still many more out there to find, so we keep spraying honey wherever we go in the tropics, and keep finding the beautiful, but deadly (to bees) bee-killing flies.

Melaloncha xanthocauda, femal

Melaloncha berezovskiyi, female

Melaloncha acoma, female