Using publicly collected data to study dragonfly swarms: Part 1

It’s October and most of the dragonfly swarming activity has stopped for the winter.  As promised, it’s time to share what I learned about dragonfly swarms from the data that I collected from my readers this summer.  But first, a huge thank you to the many people who took a few minutes out of their day this summer to satisfy the scientific curiosity of this entomologist!  I never dreamed I would get as much participation in this project as I did, nor that the interest in this topic would be so great.  In fact, this “little side project” of mine ended up consuming a massive amount of my time this summer.  I got SO much data I think I can actually get a publication out of it at some point!  I may present the data at an aquatic sciences conference next summer as well.  Thank you thank you thank you for making this project a success!  I can’t describe how happy it’s made me to be working on dragonfly research again and this was made possible in part due to my fabulous readers.  I really can’t thank you enough.

dragonfly swarm banner

I’m going to present my swarm data in three parts.  Today will be the fluffiest and shortest post and will include some basic stats, some information about the species that were identified from the swarms reported, and some interesting facts.  Next time I’ll present my maps of the swarms with some more detailed information and I’ll finish up this series with some analysis of the data and conclusions in the third post.

Without further ado, some interesting facts about the dragonfly swarm data:

  • I received 639 reports of dragonfly swarms since I started collecting data on my blog in late July
  • Swarms were reported in nearly all 50 states.  The exceptions were Alaska (didn’t expect them there), Hawaii (ditto), Wyoming (perhaps because the tiny population = lack of observers?), and Louisiana (very strange!).  These swarms are very widespread in the US.  I would recommend caution though: don’t read too much into this fact just yet and I’ll come back to the distribution info in the next post!
  • The states with the 5 largest total numbers of dragonfly swarms reported were: Illinois (97 reports), Wisconsin (56 reports), Indiana (52 reports), Iowa (50 reports), Missouri (38 reports)
  • The states with the fewest total reports of swarms reported were: Alaska, Hawaii, Wyoming, Louisiana (0 reports), Colorado, Delaware, Idaho, Maryland, Massachusetts, Nevada, New Mexico, North Dakota (1 report)
  • Non-US swarm reports came from: Canada: Ontario (8 reports), Saskatchewan (1 report), British Columbia (1 report); Belize (2 reports – state/territory unknown to me)
  • The greatest number of migratory swarms were reported in: Florida (11 reports), Nebraska (7 reports), Oregon (6 reports), Iowa (5 reports), Wisconsin, Washington, Montana, North Carolina, Illinois (3 reports)
  • There were massive swarm events in several major US cities, including Milwaukee, St.  Louis, Minneapolis, Omaha, the Chicago area, and Long Island in NYC
  • The most commonly reported dragonflies in swarms (either IDed by the reporters or from photos submitted by reporters) were the green darner (Anax junius), the wandering glider (Pantala flavescens), the black saddlebags (Tramea lacerata), the Carolina saddlebags (Tramea carolina), the blue dasher (Pachydiplax longipennis), and the variegated skimmer (Sympetrum corruptum).  Photos of all of these species can be found on my common migratory species and less common migratory species posts from earlier this summer.  A few other species were reported to a much lesser extent.
  • Every type of static swarm that has currently been identified was reported by numerous witnesses and in several regions.
  • Reports from rural areas were more common than reports from urban areas, but not significantly more so
  • Reports from the midwest were much more numerous than reports from the west or the east.  You’ll see this for yourself when I present my swarm maps in my next post!
  • Female reporters vastly outnumbered male reporter.  I found this completely fascinating!  And people say women don’t like bugs.
  • There were more people who were fascinated by their swarms than people who were terrified of the dragonflies they saw.  This makes me happy.

One of the things that made this project so fun was finding information that other people had posted online about swarms they’d seen in their areas.  A few of my favorites included:

  • Bryan Pfeiffer has a great blog called The Daily Wing.  This summer he came across a swarm of wandering gliders that prompted him to write a great post about dragonfly swarms.  This is a really good scientific account of dragonfly swarms – and thanks, Bryan, for encouraging your readers to submit reports to me!
  • Pauline at Perrenial Student writes a great account of her encounter with several dragonfly swarms.  I love the lyrical quality of this account.  A lot of reports that were submitted to me sounded just like this.
  • Still on the Track contributer Jon Downes tells a tale of a gigantic swarm he witnessed as a child in Hong Kong that was very unlike what people see in the US.  The post included the glorious photo of the couple struggling through the swarm on a beach that I used in a previous post.
  • Jim McCormac attempted to put Ohio’s residents at ease about the massive numbers of dragonflies they were seeing in an article on his Ohio Birds and Biodiversity blog.

Dragonfly swarms were SO conspicuous this year that they made the news in several areas as well:

Clearly, dragonfly swarms were big news this summer!  In fact, I think this was a particularly special year for dragonflies.  I’ll go into this further in the third post in this series, but I’ll say this: I’m VERY happy I started collecting dragonfly swarm data when I did!

Well, that’s it for today!  Next time, I’ll dive into the distribution of the swarms and include a series of my swarm maps.  One of the best parts of this project for me was adding the pushpins to my Google Earth map and seeing how the patterns changed over time.  I hope you’ll find it interesting too!


Have you seen a dragonfly swarm?

I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes!



Want more information?

Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!


Unless otherwise stated, all text, images, and video are copyright © 2010


3 thoughts on “Using publicly collected data to study dragonfly swarms: Part 1

  1. Hi Dragonfly woman,

    I love your blog and the dragon fly.My ideal pic will be of a dragon fly sitting on a cattail.I recently came across the term odding.I found it so interesting.I googled it and led me to ur page.I found a swarm of dragon flies in Chennai.I live in Anna nagar East.We live on the third floor.I always see a swarm flying during the day.I wonder why.Do let me know if this is of some use to you.

    • Thanks! I’m glad you like it! Do you have a date when you saw your swarm? I’ll add your sighting to my data, but it would be best if I have a date attached to it. And they’re likely out during the day because a) that’s when dragonflies are most active and b) that’s when the prey species the dragonflies are eating (flies, ants, termites, etc) are active. If you’ve got lots of prey insects cropping up, you’ll often see dragonfly swarms in the same area. Fun! It’s great to have another non-US swarm to add to my data!

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