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SKEPTOID BLOG:

My Fascinating Back Yard: Dragonflies

by Dani Johnson

March 2, 2013

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Donate As scared as I am of creepy-crawlies, I have always been simultaneously fascinated by them. The creepier they look the more I want to look at them. Now, I don't go as far as touching them with my bare hands, I usually capture one in a glass jar (with a lid that can seal tight!) or look it up online if it's something I don't have the guts to "handle". I've even come to love a few species of insect even though they make my skin crawl if one flies towards my face or crawls up my shoe. Using "love" and "insect" in the same sentence is something that I'm still getting used to, but I've had an amazing time learning about them. My first instinct is to squash the creepy looking things, but something in me always reminds me that I can take an opportunity to learn something rather than to kill something. I have since discovered that there are many fascinating insects to look at and learn about right in my back yard and let me tell ya, Georgia is a place that is rife with creepy-crawlies of many different shapes, colors and smells. Dragonflies are one of the most fascinating insects that we have around here and they do amazing things that I had never known about until I happened upon an article about them and stuck around to read the entire thing.



Adult male Common Whitetail Dragonfly Credit: Bruce Marlin

Dragonflies are carnivorous insects belonging to the order Odonata that have free moving heads with big bulging eyes and a long and thin body with six legs and four transparent wings. The only other insect in the same order are the damselflies which look very similar to dragonflies except they hold their wings vertically when at rest rather than horizontally and their four wings are identical in shape where the dragonfly's hind wings are broader than their forewings. Unlike some insects, dragonflies don't use their legs for walking, Instead, their legs are for hunting. They're actually more like fingers than legs. They will use their incredible sense of sight to locate a smaller insect and zoom at speeds up to 36MPH to their prey and grab them with their legs and haul them off to have a snack.

Since Dragonflies have four wings that are able to move independently they're pretty much like little helicopters that eat mosquitoes, flies, ants, bees and wasps among other smaller insects. They can also rotate each wing slightly forward or backward on its axis. It's really spectacular to watch a dragonfly in flight. They can zip straight up or down, make hairpin turns, hover and fly backwards. Yes, they can even fly backwards.

Dragonflies can live as long 4 years but only about 2 months of that is spent as a mature adult. Unlike butterflies or mosquitoes, they go through only three stages of development: egg, nymph and adult. Nymphs live underwater for the duration of the nymph stage and they will stay this way for up to 4 years before going out into the air to use their lungs to breathe. Breathing triggers the last molting process and an adult emerges and leaves behind a shell called exuviae, much like a cicada.

Believe it or not, dragonfly nymphs not only breathe through gills that are in their rectum but when they need to make a quick getaway all they have to do is expand their stomachs to suck water in through their back-hole and push to propel water out of their bum and they're outta there faster than you can blink. They also poop out of the same hole. Woah, I don't imagine that would be very comfortable. They also have this really cool mouth part called the mask that is basically a set of pincers that fold up and sit right under their head when not in use. They use the mask to reach out and grab prey to munch on.

I love it when a storm of dragonflies emerges in our back yard and I get to watch these beautiful creatures in flight. Even though it's sad to see nature at work sometimes, it's even amazing to watch the birds that frequently dip down and grab a quick and easy snack while the dragonflies are out. I encourage you to spend a while in your back yard observing some of the creatures that live out there. There's so much to see, just go and sit down in the grass for 15 minutes and you'll find that there's a fascinating world that's been right under your nose this entire time.

Sources:

http://www.dragonfly-site.com/dragonfly-life-cycle.html

http://science-ed.pnnl.gov/pals/resource/cards/dragonflies.stm

http://insects.about.com/od/dragonfliesanddamselflies/a/10-Cool-Facts-About-Dragonflies.htm

by Dani Johnson

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