Tuesday, April 4, 2023

Dragonhunter


Gala Keller sent us this photograph of a huge dragonhunter larva she found on their stream.  It was left "high and dry" on their creek path when the flood water receded.  This MDC Field Guide has lots of information on dragonfly larvae but lets look at a few of the highlights.

Adult dragonhunter - Donald Lake on Wikimedia

The dragonhunter, Hagenius brevistylus, is the largest of the clubtail dragonflies in the US and the only member of that genus.  Adults feed on large insects including other dragonflies and darners.  They are known to feed on monarch butterflies, eating the thorax and abdomen first to avoid the greatest concentration of the toxins acquired from feeding on milkweeds. 

Typical dragonfly nymph - MDC

Now about dragonfly larvae aka nymphs in general, and a few "fun facts." Note to self- spending too much time talking with 5th grade WOLF Students!

  • The larvae are all aquatic and live in the stream bed until they molt into flying adults.
  • They are ambush predators of small aquatic animals, using their lower scoop like jaw which covers most of the bottom part of their heads.
  • They have a chunky body with large eyes.
  • "Gills are located inside the rectum (unlike those of damselflies, which extend from the hind end like 3 leaf like tails). They breathe by drawing water in and out of their hind end. talk about bad breath!  By forcefully expelling this water, the animal can also move quickly in a form of jet propulsion."  You can see it "exhale" at the last of this video by our own Linda Bower.     Now wasn't that fun?
  •  The nymphs undergo several molts which can occur over several years. They finally crawl out of the water to a safe place, shed their skin, and emerge as a young adult. In the next days or week, they complete their maturation.

For more on Dragonfly and damselfly action check out our Linda Bower's Nature in Motion videos.