Rhionaeschna multicolor

With a blog called The Dragonfly Woman, you might assume that I like odonates.  And I do!  I think they’re amazing, beautiful creatures that deserve far more attention than they actually get.  I know I’ve talked about why I think dragonflies are the best insects  before, but today I’m going to share 5 more fun facts about dragonflies to add a little spice to your Friday.

Perithemis intensa

1.  Damselfly nymphs have 3 leaf-like gills at the tip of the abdomen.  These gills are one of the distinguishing characteristics of damselflies in fact.  They’re thought to help damselfly nymphs breathe more effectively underwater, but…  Scientists have removed all the gills from damselfly nymphs to see how it impacts their development and growth and… surprisingly little changes!  It’s possible that these “gills” are actually used for something else.  One hypothesis: they wave the gills around in aggressive encounters with other damselfly nymphs, so they might actually play a bigger role in conflict management than respiration.  More research might help us understand the role these structures play in greater detail.  More odonate research = fun!

Pachydiplax longipennis

2.  Odonates go through a non-reproductive maturation stage after they molt into adults.  In many insect species, newly emerged adults can get right to the important things: finding mates and getting busy making offspring.  Most odonates have to wait at least a few days, sometimes even a few weeks, before they can actually start mating.  This is called the teneral stage.  Teneral odonates are often a different color than fully mature adults, especially in males, so you can often tell whether a dragonfly or damselfly is able to produce offspring just by looking at it.  This can make identifying a dragonfly a bit more difficult as it increases the number of possible colors any one species exhibits, but it’s also nice to be able to easily determine whether a dragonfly is teneral or not.

Anax junius

3.  Some dragonflies use puddles or rain pools inside plants or trees to reproduce.  Dragonflies in temperate regions such as the US typically spend more of their life as nymphs than as adults, a year or two as nymphs and less than a month as adults.  The opposite is often true in tropical regions close to the equator where some species can transform from an egg to an adult in a few short weeks. Nymphal developmental times in these regions can be short enough that puddles, or even little pools of water collected in the folds of plants during rains, are great places to raise the kids.  Imagine spending your entire childhood in a single tree hole!

Pachydiplax longipennis

4.  Some dragonflies lay eggs in water that is saltier than the ocean.  There are very, very few insects that live in the ocean.  Several ideas have been proposed to explain why this might be (I’m going to write a post about it sometime), but one of the obvious reasons is that ocean water is salty and some insects might not be able to handle it.  That doesn’t seem to be a problem for some dragonflies though!  Some species, such as the seaside dragonlet (Erythrodiplax berenicei) can successfully produce offspring in water many times saltier than the ocean.  Reproducing in brackish water.  How cool is that??

Anax junius over cattails

5.  There are a number of dragonfly sanctuaries in Japan that were established specifically to protect dragonflies.  Unlike most places in the world, dragonflies are an important part of Japanese culture and have a lot of positive symbolism attached to their appearance in the spring.  As such, dragonflies enjoy protections in Japan that few other countries provide.  Japan is home to several wildlife sanctuaries created solely to provide essential habitat for dragonflies so that they can continue to survive in the face of increasing urbanization.  I hope that other countries, including my own, will follow Japan’s lead in the future as water resources become more scarce and dragonfly habitats are eliminated.  Dragonflies are amazing, and they deserve some protection as far as I’m concerned!

Yep, dragonflies are really cool insects.  They have strange structures and strange behaviors and live in strange places.  They’re quite beautiful too!  I know there are people who don’t appreciate dragonflies in the world, but I don’t always understand those people.  What’s not to love?  As the sticker on the back of my car says, dragonflies rock!

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Black rat snake

Black snakes are THE most disturbing thing I have ever encountered. They disturb me to the very depths of my soul. However, when this black rat snake slithered out of the brush along the path, I didn’t feel my breath catch in my throat or my heartbeat increase instantly. Nope, I thought, “Wow! A snake! Something to photograph!” and actually went running after it to get a better shot. Apparently having a camera between me and a snake makes me entirely fearless!

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The book has two main goals as I see it.  First, it introduces the reader to the benefits of aquatic insects and succinctly explains why everyone should appreciate them.  My only (minor) complaint is that the book focuses almost entirely on their usefulness as biological indicators of water quality to the near complete exclusion of other benefits they provide, but it’s understandable.  Aquatic insects do play a very important role in monitoring water quality around the world and that importance is rarely advertised to the public.  The book also provides basic information about aquatic insects.  Each section begins with information about an order (their structures, life histories, and role as bioindicators) to teach the reader a little about each group.  There’s a fair amount of knowledge contained in this 160 page book!

The second goal of the book is to help readers see aquatic insects through the eyes of the scientists who study them.  After a brief introduction to a group at the start of a chapter, you read through a series of stories (mostly non-fiction) that allow you to follow along with an aquatic entomologist as he/she works.  These stories are what attracted me to the book.  A lot of big name aquatic entomologists talk about their work and fascinations with aquatic insects while simultaneously teaching the reader a bit about a specific insect.

The stories are, I think, beautiful.  Many are love stories from scientists to the organisms that both enthrall them and provide their bread and butter, but there is a lot of variation in story styles and topics.  Ever been curious about how scientists discovered that the giant water bug Abedus herberti leaves streams before flash floods?  You’ll find out in the story by Dave Lytle.  Or maybe you’ve wondered if aquatic insects are useful in murder cases.  John Wallace can answer that.  The book contains stories about mayflies, stoneflies, caddisflies, true flies, dragonflies/damselflies, bugs, and beetles written by researchers studying a huge variety of topics.  In essence, it provides an overview of what aquatic entomologists actually do while giving you a unique insight into their psyches.

If you have an interest in aquatic entomology, this is a great little book to add to your collection.  The approach is rather unique and the book presents a viewpoint you’re unlikely to find anywhere else.  It’s a short book, but it’s full of inspiration and information.  I highly recommend it!

Wet Beaver Creek

In the spirit of the book, I would like to share a very brief story about an encounter with an aquatic insect I’ve had.  About 5 years ago, I helped out a Park Service friend who was part of a team developing an aquatic monitoring plan for Arizona’s national monuments.  They wanted an outside opinion about the effectiveness of their plan and invited me to evaluate it.  We met up at the tragically named Wet Beaver Creek near Montezuma’s Well in central Arizona and got to work, spending the rest of that day and the following day sampling the insects in the stream.  It was great!  And the monitoring plan was sound too.  Fun, fun, fun!

Most of the team went back to Tucson at the end of the second day, but my friend and I stayed another night.  Lacking anything better to do, we wandered up to the Well in the dark, leaned against the railing overlooking the big water-filled crater, and talked about the monitoring plan and aquatic insects for about an hour.  I was really enjoying the whole experience!  Two days of collecting bugs in a beautiful river was making me very content with the world.

Right about as that feeling started to sink in, however, I felt something bite my calf just below my shorts.  Just a tiny pinch, so I swatted my hand at it and didn’t think more about it until I felt another one.  And another.  Then another.  The moon was very bright, so I eventually looked down to see what was nipping at my legs.  They were no see ums (aka, biting midges), tiny flies in the family Ceratopogonidae that are aquatic as larvae and terrestrial as adults!  Their common name stems from the fact that they’re so small they’re hard to see, but they are bloodsuckers.  I hadn’t ever encountered no see ums, so I thought, “What damage can such tiny flies possibly cause?” I started jiggling my legs a bit to discourage their landing on me and winced slightly whenever one bit me, but didn’t worry about it that much.  I fell asleep that night thinking, “That wasn’t so bad…”

Fast forward to the next morning.  Remember that photo I shared in my post about the downsides of entomology, this one showing all the bites on my legs?:

No see um bites!

That was what I woke up with!  SO many bites, SO itchy, all over my legs and arms.  The 3.5 hour drive home was excruciating because I couldn’t stop scratching.  I essentially doused myself in hydrocortisone when I got home.  Then I counted my bites.  I had over 300!  THREE HUNDRED!  No wonder I was clawing my skin off.  No wonder I was miserable!  300 little bloodsucking flies had feasted on my legs!

That was my only bad encounter with no see ums though.  Now I wear long pants and long-sleeved shirts, even when it’s hot.  I would rather get my pant legs wet than live through that misery again.  That night I was almost taken down by a 1mm long fly!  Never again.  Never again…

So that’s one quick little story, but I’d love to hear your stories too!  Does anyone want to share an encounter you’ve had with an aquatic insect?  If so, leave a comment below!  Let’s make our own little Wading for Bugs!  But read the book too!  Maybe, just maybe, you’ll understand aquatic entomologists like me a little better.

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Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com

I’m taking a break in the Science Sunday posts this week to share a few late breaking dragonfly swarm tidbits.  A Swarm Sunday!  In the middle of the winter!  I’m excited.  Are you excited?  :)

First, the dragonfly swarm activity (at least based on the reports that I get from mostly English-speaking people) seems to be heaviest over Central America recently.  A few weeks after the end of the US and Canadian seasons, I started to get reports from Central America.  I can’t say for sure that the swarms that left the US mainland in October ended up in Belize, the Yucatan Peninsula, and Honduras a few weeks later, but…  There might be a connection between the two.  Mark recapture studies or radio tracker studies would be necessary to confirm this, but there are published accounts of dragonflies flying out over the water in the southern US during the migration season and other scientists have hypothesized that they are likely to end up somewhere in Central America.  It will be interesting to see if this pattern of US migration followed by a surge in dragonfly activity in Central America continues over the next few years as this is the second year I’ve observed the pattern.  Dare I hope that my data might even suggest possible places where these dragonflies are overwintering?  That would be incredibly exciting!

I wanted to highlight one recent Central American swarm.  My aunt rented a condo in Costa Rica this month and she invited nearly her whole family down to visit while she was there.  My sister went for a week, then sent me a video last weekend, out of the blue, that she’d taken of a massive dragonfly swarm that had formed right over the condo.  It had lasted three days and likely involved millions of dragonflies!  I was seriously jealous, especially considering I was the only person invited who wasn’t able to go to Costa Rica and missed out an enormous dragonfly swarm on the beach too.  But then my aunt’s brother-in-law (who’s renting a nearby condo) sent me photos of the swarm yesterday that made me swoon a little.  Check them out:

Dragonfly swarm in Costa Rica. Photo by David Alexander.

Dragonfly swarm in Costa Rica. Photo by David Alexander.

Sunset.  Beach.  Ocean.  Dragonflies!  Oh, I wish I’d been able to see this one!  Look how beautiful it was!  (Granted, if I had been there I would have spent the entire three days making scientific observations, but I’m an entomologist with an interest in natural history and behavior.  That’s what we do!)  I love these photos beyond their aesthetic appeal though.  For one, the dragonflies are so much more distinct than in most of the photos I’ve seen of this behavior – or even taken myself!  This is an incredibly difficult behavior to capture photographically because there is so much movement and so much depth.  You can only see silhouettes in these photos, but you can tell without a doubt that they’re dragonflies.  I also like that the photos are taken at sunset as that is the time of day this behavior is most commonly observed.  Most of the photos people have sent me understandably show daytime swarms.  Sunset swarms are much, much more common though, so it’s nice to see a few shots of a swarm in a more typical setting.  These photos are thus an excellent representation of the behavior.  Exciting!

The Australian swarming season should be starting up soon too.  Last year, I got several reports in February and March, so I’m hoping to get a repeat of that.  Granted, there was a ton of flooding in Australia last year, which may have led to the surge in dragonflies reported in many Australian news reports (yes, I watch Australian news reports about dragonflies.  Doesn’t everyone?) as well as the boom in swarming activity/reports.  It’s going to be interesting to see what happens this year!

It’s exciting to see data flow in even during the northern hemisphere’s winter.  Reminds me that the next US dragonfly swarming season is just 5 months away.  I can’t wait to see what happens next!

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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!

Thanks!

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Want more information?

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

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Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com

For today’s special Friday 5+1, I’m going to share a series of photos I took of the eggs of the giant water bug Lethocerus medius a few years ago that show how they grow as they develop.  It may a little difficult to see if you don’t spend as much time around these things as I do, but compare the Day 1 eggs to Day 6 eggs and you should be able to see the change clearly.  I’m also going to give you a bit of commentary so you know what to look for.  Let’s start at the obvious place…

Day 1.  Lethocerus medius eggs start off just shy of 3 mm long and about 6 mg, a substantial insect egg.  This species is an emergent brooding giant water bug (see my post about giant water bug child care for more information), so it lays its eggs on vegetation out of water.  As you can see, the eggs are very tightly packed so that most of each egg is touching the others with only a small part of the top free:

Day 2. On the second day, things look rather similar from the outside, though the eggs get a little taller and a little heavier:

Day 3.  By day 3, the eggs have gained almost half a millimeter in height and 0.2 mm in width.  The weight has gone up too, nearly 2 mg.  You can start to see the eggs bulging at bit at the top:

Day 4. The eggs are growing more noticeably now, gaining another 0.5 mm and 2-3 mg overnight!  You can see how the eggs start to crowd each other a bit.  They’re fixed in place at the bottom, but they start to spread out at the top so that they can all fit:

Day 5. By day 5, the eggs have stopped growing up and begin to grow out a bit, adding 1/10th of a millimeter and another 2-3 mg in weight.  The eggs are now over 4 mm tall and 2 mm wide and weigh nearly 13 mg! The eggs continue to spread apart at the top end as they increase in size so that you begin to see gaps between the eggs and can start to see the sides of the eggs as well as the tops:

Day 6. During their last day in the egg stage, the eggs have topped an enormous 5 mm (that’s HALF A CENTIMETER!  Huge!) in height, nearly 2.3 mm in width near the top of the eggs, and reached 14+ mg!  These are truly big eggs now, and have nearly doubled in height in 6 days.  You can see nearly all the way down to the stick in some of the gaps between the eggs and the eggs themselves look like they’re ready to pop:

If they make it this far, you’ll usually see the following events the same night.  Hatching:

… and then the newly hatched nymphs swim away, leaving behind only a stick and some empty shells:

And there you have it!  A wonderful set of growing insect eggs! Lethocerus medius isn’t the only water bug that exhibits this amazing growth either.  Other giant water bugs have shown similar patterns, including a mix of emergent brooders and back brooders.  Growing eggs seem to be quite common, if not universal, within the family to which the giant water bugs belong, the Belostomatidae.  Just one more way that giant water bugs are among the most amazing insects ever!

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