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Dragonflies & Damselflies Spear Prey With Lower Lip

7-27 dragonfly mouthpart 077Dragonflies and damselflies are unique among aquatic insect larvae in that they have a greatly enlarged hinged lower lip, or labium, which they can rapidly extend outwards to capture prey. When retracted, the prehensile labium fits like a mask over the face or is folded flat beneath the insect’s head. When hunting for prey, the dragonfly larva uses its labium like a speargun. It shoots forward as far as half the larva’s body length away, and moveable hooks on the front edge grab the prey. There are no muscles at the hinge/joint, leading entomologists to believe that the labium is extended by increased blood pressure caused by abdominal muscle contraction. It unfolds at a right angle, and extends extremely rapidly, faster than most prey can react. (photo: cast skin of dragonfly larva from which adult dragonfly emerged)

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8 responses

  1. As always, your column is fascinating. I look forward to reading it every single day. I’ve probably said that before, but that’s what goes through my head every time I see a new post!

    July 27, 2015 at 9:45 am

    • I take your comment as a huge compliment, as you are obviously a fellow naturalist. Many thanks.

      July 27, 2015 at 12:36 pm

  2. For goodness sake! So… once they have speared the victim, do they munch it, or sip it, or absorb it, or…??

    July 27, 2015 at 10:34 am

  3. Elizabeth

    I think I read somewhere that dragonflies are the most successful of all the world’s predator species – catching the greatest percentage of prey pursued and racking up an impressively high number of kills. Do you know if this is so? I sure appreciate what they do to the black fly population.

    July 27, 2015 at 10:45 am

    • I am not sure how they measure up to other predators but they do kill 70 % of their prey. From Nature magazine: “dragonflies anticipate the movement of their prey by steering their body into the projected flight path, even as their head and eyes still track the quarry in real-time.” Pretty impressive!

      July 27, 2015 at 12:43 pm

  4. Ruth

    Is that a moth on the cast skin?

    July 27, 2015 at 1:02 pm

    • Good eye! That is actually a wing “bud” – where the larva was developing wings that greatly expand once it’s shed its skin and it pumps blood into them. Didn’t see the “moth” until you commented!

      July 27, 2015 at 1:11 pm

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