Are wingless fliers Nature’s best hitchhikers?

by Ricardo L. Palma, Curator of Terrestrial Invertebrates

Evolving without wings, humans dreamed about flying for thousands of years… but only just over 100 years ago they invented a heavier-than-air machine which could fly and take them to the skies.

However, long long ago, natural evolution had already provided the opportunity to fly to creatures without wings. Yes, these wingless animals acquired the ability to “fly” by using Nature’s “aeroplanes”!

Typical groups of animals that live their entire lives flying by “hitchhiking” are most parasites of birds and bats. All lice and feather mites, many fleas and some wingless flies move about holding safely onto their flying hosts. However, some bird lice have become “double” hitchhikers by acquiring the capacity of taking rides on flying insects, which are not their regular hosts but which “land” on the bird’s plumage with other purposes, like engorging themselves with the warm blood of the host.

This phenomenon, known as “phoresy” or “phoresis”, allows lice to move from one host to another even when there is no close contact between them. For a louse, it is certainly a most convenient way to disperse and invade new hosts, without having to wait until its host touches another. The most frequent flies used by lice to hitchhike are called “louse-flies” because they are flat (like lice), and they are attracted to birds to feed on their blood.

Left: A louse-fly carries a hitchhiking louse from a Japanese crow, attached to one of the fly’s abdominal hairs. Right: detail of same louse. Photos by Rokuro Kano, Tokyo, Japan. © Rokuro Kano

Left: A louse-fly carries a hitchhiking louse from a Japanese crow, attached to one of the fly’s abdominal hairs. Right: detail of same louse. Photos by Rokuro Kano, Tokyo, Japan. © Rokuro Kano

However, parasites are not the only creatures able to hitchhike on flying insects… soil mites, false-scorpions and other small invertebrates which normally live in the leaf litter have also “learnt’ to move around by holding on to the legs or body of common flies, mosquitoes and crane-flies.

A common housefly carries three false-scorpions (arrowed) attached to its legs. Photographer unknown.

A common housefly carries three false-scorpions (arrowed) attached to its legs. Photographer unknown.

Finding and collecting or photographing flying insects with hitchhiking passengers is infrequent and not easy. I have been collecting and observing lice living on birds for over 45 years and I have not yet been able to record a phoresy case. However, a group of researchers working on Tiritiri Matangi Island in the Hauraki Gulf, near Auckland, have collected a louse-fly which has three lice attached to its body. Comparing them against other louse samples kept in the Te Papa collection, I have identified the hitchhiking lice as originating from a saddleback, a unique endemic New Zealand bird, which now only lives on islands free of mammalian predators.

8 Responses

  1. Claudio Palma

    Explained well. Even the flies have their own ‘pets’, so tiny too.
    Great pics to show such detail.

    Reply
  2. Steve Marder

    Fascinating — with photos to match — and the comments support that view! The comments are also edifying: Living in the United States, I didn’t even know such a thing as an electric fly swatter existed! Great job, Ricardo! I very much look forward to many more fine mini-articles from you.

    Reply
  3. Graciela Albrecht

    Great stuff Ricardo.
    Just a comment regarding; what you mentioned about the Saddleback. This bird is not only found on islands free of mammalian predators, but here in Wellington at Zealandia. Nice and close for you to look for the hitchhiking lice.
    Saludos.

    Reply
  4. Ali

    Hi Ricardo
    Nice.
    I also found a Hippoboscid fly with 2 attached lice in Tchagra australis .
    Thinking to use it for SEM or not!

    Reply
  5. tepapamuseum

    Hello Julia, I asked Ricardo and he replies…

    Houseflies are like humans… they hate windy and cold weather. Therefore, some houseflies are still around at this time of the year because they prefer to live indoors, where you keep a suitable temperature and humidity for them, as well as food.

    Now, regarding their immunity to fly-killers, that may be because they have developed resistance or immunity to insecticides. In other words, as you said, they may be a new resistant breed. I would suggest you change the insecticide you are using, by carefully comparing the active ingredients in each type of insecticide.

    Otherwise, do what I do, get an electric fly-swatter and electrocute them.! Not only it is fun to do it but, also, flies will never become immune to electricity.! :)

    Reply
  6. Nomi Wald

    As usual, nature excels all what humans can do. It is so interesting!! Thank you Ricardo.

    Reply
  7. Elaine Engman

    Very interesting article and great pictures!

    Reply
  8. Julia White

    Thank you, I found this really interesting, especially the fact that a louse-fly, had 3 lice attached to it.
    Perhaps you could tell us why we think there’s a new breed of fly around this year, its immune to flykiller and I still had flies in the house right up until late May.

    Reply

Leave a Reply

  • (will not be published)