Endless flies most beautiful

January 16, 2013 • 3:57 pm

By Matthew Cobb

hedgehog
A Hedgehog fly, aka Adejeania – a Peruvian caterpillar parasitoid. “Groucho fly” would be better. The “cigar” is a pair of enlarged palps, probably used to detect prey. (c) Stephen Marshall

Like Jerry, I study what many scientists call ‘The Fly’ – Drosophila melanogaster. Unlike many of our colleagues, however, we both know that other flies are available, and that in some ways D. melanogaster has been turned into a piece of laboratory equipment , for we have virtually no idea about what it actually gets up to in the wild. Both Jerry and I have studied other species, though only (I think) closely related species of Drosophila. Heavens, we’ve even gone hunting for them in Africa (guided, and in Jerry’s case alongside, the sadly departed Daniel Lachaise). (In 2006 Jerry and I published a memorial article to Daniel, which is sadly behind a paywall).

However, any feeling that I had the slightest idea about the variety to be found within my chosen study group – Diptera – has been blown away by reading Stephen A. Marshall’s stupendous new book, Flies: The Natural History and Diversity of Diptera, which appeared at the end of last year. I bought myself a copy for Xmas, and unless you are a thorough dipterophobe, I urge you to order a copy NOW! Both the pictures and the text will enlighten and amaze you. As E. O Wilson rightly says: “Stephen A. Marshall has delivered one of the most beautiful and useful accounts of insect life ever written.

Steve even makes me feel not so bad about my Drosophila-centred knowledge – “The genus Drosophila, with some 1,500 species, is larger and more diverse than most families of living things.”

Steve is based at the University of Guelph in Ontario and is both a skilled entomologist and a great photographer. I’ve scanned a few of the pictures, with Steve’s permission (apologies to all for any crappy scanning and cropping). Most of the hundreds of images show flies in their natural surroundings, a very few are of skewered museum specimens and there are loads of pictures of the larval stages.

There is a great section on the various flies that live in and around streams around the world – many of them nasty bitey things that make those beautiful areas relatively inhospitable (I’m looking at you, Highlands of Scotland). I always wondered what all those biting flies did when there aren’t people about, and answered myself by saying ‘well they must bite other mammals’. That’s no doubt true, but Flies shows us that they also bite other flies:

Here’s a biting midge taking a meal from a crane fly:

midge

Here  Forcipomyia biting midges suck the blood from the wing veins of a lacewing.

midge2

(c) Stephen Marshall

Flies is divided into three parts – Life Histories, Habits and Habitats; Diversity (the bulk of the book) and Identifying and Studying (including some keys that look user-friendly, but will be difficult, because taxonomy is).

One of things that soon becomes clear is that apart from biting and eating crap, many flies are cunning kleptoparasites – they steal predator’s food. Here are a couple of dramatic photos.

First, “Adults of milichiid genus Desmometopa are often specialized kleptoparasites, swiftly attracted to Honey Bees captured by other arthropods such as robber flies or spiders, like the Cuban lynx spider shown here.”

kleptos
(c) Stephen Marshall

These Olcella flies (can you see both of them?) are getting a quick meal from some hapless ant that is being snarfed by a spider (that’s my caption, not Steve’s):

klepto2
(c) Stephen Marshall

The Diversity sections is divided into three main chapters, corresponding to the current classification of the order (this has changed a number of times!) – the Lower Diptera (includes mosquitoes, crane flies and lots and lots of midges), the Lower Brachycera and Empidoidea (the former includes Horse flies and Bee flies, the later are the “Dance flies”), with the final, and biggest, chapter, devoted to the Higher Brachycera or what I still call the Cyclorrapha, which includes almost half of identified fly species, including Drosophila melanogaster.

Each of these chapters consists of a brief explanation of the classification – invaluable for an ignoramus like me – followed by page after page of fantastic photos, each with an informative caption.

Here are some of my favourites. First, members of the Rachicerus genus looks like they have multi-segmented comb-like antennae. Why? Their larvae live under the bark of trees where they eat other larvae:

antennae
(c) Stephen Marshall

A male Lindneromyia – found in soft fungi throughout the world (NO IT HAS NOT BEEN PHOTOSHOPPED). The eyes of the female are small and separated. Presumably either the male has to track the female for mating, or he is subject to some specific natural selection pressure that means he needs what looks like 360 degree vision.

eyes
(c) Stephen Marshall

Bromophila caffra from Africa. This species, like others in its genus, “has the startling habit of ejecting yellow fluid from its mouth”. Note it does not have any ocelli – the three tiny extra eye-patches on the top of the head that are used for detecting polarised light. Even Lindneromyia has them.

(c) Stephen Marshall
(c) Stephen Marshall

And finally, can you guess what is weird about this Ormia fly? (Answer below the photo)

nocturnal
(c) Stephen Marshall

It’s nocturnal. Very few flies fly in the dark. These parasitise crickets, using  specially-enlarged structure to detect the vibrations produced by their prey. Look at those long legs!

This is just a fraction of the wonders that await you inside the pages of this marvellous book!

Stephen A Marshall (2012) Flies: The Natural History and Diversity of Diptera. Firefly Books. ISBN-13: 978-1770851009

31 thoughts on “Endless flies most beautiful

  1. Good stuff Matthew

    I didn’t understand this bit:-

    “…members of the Rachicerus genus looks like they have multi-segmented comb-like antennae. Why? Their larvae live under the bark of trees where they eat other larvae”

    Are you saying these frilly antennae are better at picking up the signature** of buried larvae so that the adult fly can lay her own larvae nearby assuring food for her own?

    ** The signature being chemical or sound?

    1. Sorry Michael – my fault. The two sentences aren’t connected! There is no answer – as far as I know – to the “why?” The stuff about their habits was add for colour, and should logically have come before the question. They are very odd antennae, so there is presumably a functional explanation, but I have no idea what it might be.

      1. Thanks for the answer Matthew. I learned today that arthropod antennae are incredibly multifunctional. I had no idea…

        I did a general search for the functions of insect antennae & I came up with this [no doubt] incomplete list ~ the length of which astonished me:-

        Detect smell
        Sex pheromone detector
        Humidity sensor
        Touch & Sound [almost the same thing at insect scales?]
        Air speed indicator
        Solar compass on butterflies!
        Gyroscope device on moths!!

        I would suppose that antennae may also be used for display to attract mates or intimidate rivals although I’m guessing

        On bugguide.net I found THIS PICTURE comparing male & female antennae of Rachicerus obscuripennis
        According to the text underneath the pic the male has larger combs. If that’s not just chance in such a small sample, perhaps that’s a clue to function. For example if it is the male that seeks out the female he may need superior pheromone detection. Just a thought.

        1. That’s very interesting, Michael. And yes, antennae do all sorts of thing. Indeed, the only ‘synapomorphy’ of insects – something they all possess that no other group possesses – is the “Johnston’s organ” in the antenna, which is a sound-detector. Like you, I assume the male’s larger combs are to do with sex pheromone detection (this is the case in moths, for example), but why the odd apparently jointed structure? Why don’t other flies have them? V weird.

  2. And if you haven’t got it yet, pick up his other amazing book as well:

    Insects: Their Natural History and Diversity: With a Photographic Guide to Insects of Eastern North America.

    Thousands of photos – I’ve bought several!

  3. BilBy beat me to it… 🙁

    “So nat’ralists observe, a flea
    Hath smaller fleas that on him prey;
    And these have smaller fleas to bite ’em.
    And so proceeds Ad infinitum.

    Jonathan Swift

    I first saw the above quote in a physics textbook in 1975, on elementary particles.

    1. Most physicists know this play on de Morgan’s version of Swift:

      “Big whirls have little whirls
      that feed on their velocity,
      and little whirls have lesser whirls
      and so on to viscosity.”

      – Lewis Fry Richardson (mathematician and meteorologist, who pioneered modern mathematical techniques of weather forecasting) [ http://en.wikipedia.org/wiki/Lewis_Fry_Richardson ]

      1. Oops, that was supposed to be a Wiki quote:

        who “pioneered modern mathematical techniques of weather forecasting”.

  4. Done! With a recommendation like that, how could I resist.

    Can’t wait to get the book and read it while eating breakfast (the paleontology/forensics specialist in the house is going to be quite jealous)

  5. The book sounds fantastic. I assume it is similar in scope to Hoelldobler & Wilson’s The Ants?

    As for “most beautiful”, however… fascinating, yes. But I vote the green spider is prettier.

  6. Two questions:
    1. This is kind of a rhetorical question but if you have an answer have at it: with respect to the “Why?” question you pose on the plumose antennae of adult genus Rachicerus I ask “Why not?” Many arthropods, like flies, are holometabolous and between the larval and adult stage metamorphose into a completely different morphology and feed in a different environment.
    2. Are the kleptoparasites that feed on prey captured by spiders immune to the enzymes the spider injects to liquefy the prey’s insides or do they get there before the process begins? Are they also immune to the spider’s poison?

    1. Fair points. But “why not” needs to apply to all the other flies that don’t have those odd antennae. There must be something in their past (not necessarily an adaptation, but probably) that explains why they have them and all the others don’t. I don’t think anyone knows really about the kleptoparasites (or indeed much about the behaviour and physiology of most of the flies in Steve’s book). My hunch would be that the spider is too preoccupied by its Big Lunch to worry about the tiddlers buzzing around it. Plus those enzymes have to be digested into the prey, and the flies and just mooching around on the outside. But you could be right – especially if the flies laid eggs on the prey, then the maggots would need to be resistant.

  7. Hey, second time in a week this site has mentioned stuff I work on! Fantastic! My lab studies the acoustically-orienting flies mentioned above, but I have to correct the typo: it’s Ormia, not Ornia. And the flies are not strictly nocturnal; they are most active at dusk and dawn, although they do hunt at night as well. When we trap them we always set out a playback right at sunset.

    I really work on the crickets, not the flies themselves, but other labs have found that the hearing apparatus in the flies is remarkably co-evolved with their hosts, as if they had cricket ears on a fly body. Check out some of Andrew Mason’s work if you are interested. He’s at the University of Toronto in Scarborough.

    1. Great! This will be included in my invert lectures for next year! What do the flies use those long legs for? Feeling out their prey?

      1. Got me. Honestly, when I’ve seen them in the field the legs don’t look all that long — they have a generally less robust body than, say, houseflies, but aren’t strikingly long-legged. The females larviposit, rather than lay eggs, so they kind of dive-bomb their hosts and broadcast a number of tiny mobile larvae on and around the cricket. I am not sure they ever “feel around” for hosts.

        Mind you, as with virtually all parasitoids, we know nothing about their behavior when they are not seeking hosts. So maybe the legs are important for some other activity.

        1. Steve does say that most of the other species are yellow-ish, and looking on google for Ormia (thanks!) they all look more “normal” – yellowish, rounder, shorter-legged – than this specimen. Maybe this species does something weird. Finally, I am of course looking at it with a Drosophilist’s eyes, so it looks weird anyway…

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