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Bug of the Week: Dragonfly Nymph

Yes, our mystery insect last week was actually the exoskeleton or the shed "skin" of a dragonfly nymph.

dragonfly-nymph-exoskeleton

Dragonfly nymphs usually live under water, but they crawl onto land before emerging as adults. Exposure to the air and sun has darkened this exoskeleton and made it look, well, crispy.

You can tell the adult dragonfly has emerged because of the opening in the back of the thorax. Those white lines are the remnants or linings of the breathing tubes (tracheae) that pull out as the adult dragonfly emerges. The adult will produce new tracheae.

The one feature that really tells that this is a dragonfly nymph is the head, particularly the "mask" at the bottom of the face. Dragonfly nymphs have a special lower lip or labium that they use as an "insect net" to capture or scoop up prey and also sort of like a horse's feed bag to hold food while they eat.

In this video of a live dragonfly nymph feeding, look for both uses of the labium.

Isn't that cool?

I loved reading all the imaginative ideas about what the insect might be. Would you be interested in future mystery insects?

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If you would like more dragonfly science, try this previous post with activity ideas.

2 thoughts on “Bug of the Week: Dragonfly Nymph

  1. Sherry

    That was a highly entertaining video! And I thought my kids were messy eaters! Thank you for sharing the video. I am planning to do a lesson on aquatic insects with my children's homeschool co-op, and I look forward to sharing this video with them. I have a follow up question about the white lines. I found a cicada exoskeleton yesterday, and it had several of those lines in it. Do those rip out of the body? How can the adult form live without them? I am not quite understanding their function pre and post emerging as adults.

  2. Roberta

    Sherry,

    You are very observant. Yes, the white lines or tubes in the cicada exoskeleton are the tracheae as well.

    It is a bit complicated, but those breathing tubes are lined inside with the same material as the exoskeleton. When the insect molts, or changes the exoskeleton, the lining of the breathing tubes changes as well, coming out kind of like a sock being turned inside out. The linings that are lost re-form inside the insect and harden after molting, just like the exoskeleton on the outside does. So, the insects still have tracheae, they are just new, fresh ones.

    Have fun with the lesson on aquatic insects.

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