Don’t Exterminate Dragonflies!

Dythemis nigrescens female

Black setwing, Dythemis nigrescens, female

A few days ago, I was reading my news on Twitter and noticed a tweet by Alex Wild of  He provided a link to a page on a Terminix website.  Normally I don’t bother looking at pest control company websites because they just make me mad, but the tweet mentioned extermination services for dragonflies.  Sure enough, the page discussed services Terminix can provide to rid your yard of any pesky dragonflies that might be bothering you.

Normally I try to keep my blog as cheery and positive as possible, but as an entomologist and someone who really, really loves dragonflies, I am outraged that Terminix provides this service!  I openly admit that am opposed to pest control companies in general due to some run ins with some terribly misinformed pest control people.  I have a strong bias against these companies, so feel free to take what I say here with a grain of salt if you disagree with me – or just stop reading here.  I do begrudgingly see the utility of calling in a control company when your house is being overrun with ants or termites or some other insect that causes damage, so I’m not entirely anti-pest control company.  But dragonflies?  Seriously?  If I ever needed another reason to convince me I should never hire Terminix, this is it!

I hope no one ever uses the Terminix dragonfly extermination service.  There are so many reasons why it’s great to have dragonflies around!  Thus, I’m devoting today’s post to several reasons why you shouldn’t exterminate the dragonflies in your yards.  Give me a second to climb up on my soapbox…  :)

Rhionaeshna multicolor male

Blue-eyed darner, Rhionaeshna multicolor, male

Reason Not to Exterminate #1: Dragonflies are beautiful!

This is the most touchy feely of my reasons, but let’s face it: as far as insects go, most people think that dragonflies fall way over toward the beautiful side of the ugly-beautiful continuum of insects!  Countless people love dragonflies solely for their looks.  If that’s the only reason you hesitate to exterminate the dragonflies in your yard, it’s good enough!  People often attract butterflies to their yards, so why not let some equally stunning insects fly around with them?

Pachydiplax longipennis female

Blue dasher, Pachydiplax longipennis, female

Reason Not to Exterminate #2: Dragonflies are harmless to people

I’m frequently asked if dragonflies bite.  Yes, it IS possible to be bitten by a dragonfly.  I’ve been bitten myself.  However, getting bitten by a dragonfly is next to impossible!  You have to catch the dragonfly first, and anyone who’s ever tried to catch a dragonfly knows how very difficult this can be.  Then you have to grab the head of the dragonfly.  If you’re not paying sufficient attention to what you’re doing that you grab the head instead of the wings, well… I think you just might deserve to be bitten.  I certainly deserved to be bitten the one time I found myself in that situation!  Rest assured: Flying dragonflies will not bite.  They do not attack people.  They do not sting.  If you sit in the middle of a swarm of thousands of dragonflies, there’s probably something like a one in a trillion chance you’ll be bitten.  Dragonflies also cause no damage to your home or your garden or your lawn.  They thus present ABSOLUTELY NO risk to you if they’re just flying around in your yard!  Why pay to remove something that is completely harmless?

Pantala flavescens male

Wandering glider, Pantala flavescens, male

Reason Not to Exterminate #3: Dragonflies are very beneficial insects!

Dragonflies are superb predators of small, flying insects.  Those small, flying insects are often A) very annoying and B) carry diseases.  Most people don’t like having mosquitoes and gnats in their yards.  Dragonflies will help eliminate many of these little pests!  They’re nature’s flying pest exterminators (they’re sometimes called mosquito hawks for their mosquito chomping prowess!) so they’re great insects to have in your yard.  Why would you want to eliminate insects that prevent you from being bitten or annoyed so badly by flies that you no longer want to go into your yard?

Erythemis collocata male

Western pondhawk, Erythemis collocata, male

Reason Not to Exterminate #4: You might kill an endangered species

This is the most flimsy reason as there aren’t very many dragonflies on the endangered species list yet, but there are some and in various places around the world so I’m going with it.  I put this question to you: do you honestly trust a pest control employee to know the difference between, say, an endangered Hine’s emerald and any other large, mostly black American dragonfly?  I certainly wouldn’t!  The last time I talked to a pest control “expert” outside of my entomology department, the guy all but told me I was stupid because I disagreed with him when he said that all termites are completely white and wingless like the one in his photo.  He even argued with me when I insisted he was wrong, gave him the name of a species that was not entirely white, and reminded him of the winged stage of termites.  If a pest control expert doesn’t even understand the life cycle of one of the extermination industry’s biggest money-making pest species, I wouldn’t dare let one kill dragonflies if I lived in an area that had an endangered species flying around.

Perithemis intensa male

Mexican amberwing, Perithemis intensa, male

Reason Not to Exterminate #5: Do you really want pesticides all over your yard?

Most pesticides really aren’t that good for you.  While the makers will insist up and down that they don’t threaten human life (and some of them really don’t!), we don’t fully understand the effects of chronic, long-term exposure to many pesticides or how exposure may impact our future health.  If you call in a pest control company, you can be sure they’ll bring along a big vat of pesticide to spray your yard with.  Why take the risk?  The dragonflies aren’t doing anything to harm you or your property, so you might as well keep your money and minimize your exposure to potentially toxic chemicals.

Erythemis collocata female

Western pondhawk, Erythemis collocata, female

Reason Not to Exterminate #6: Dragonflies aren’t the problem anyway…

If you have a lot of dragonflies in your yard, they are likely there for one of two reasons: 1) you have water in your yard, either a pond or a stream, or 2) you have enough gnats, mosquitoes, or other small flying insects to meet the nutritional needs of the dragonflies in your yard.  If you have water in your yard, there’s not much you can do to get rid of your dragonflies.  You might as well move if you don’t like them because they’ll keep coming back.  If you don’t have water in your yard, something else is drawing them there – and that something else is likely going to be a bunch of little insects you don’t like having around.  Imagine a scenario: You have a lot of dragonflies in your yard.  You call Terminix and have them removed.  A few days later, your yard is overrun with mosquitoes.  Then you call the Terminix people again to have them take care of the new problem.  Maybe I’m overly cynical, but I can’t help but think this is the motivation behind the dragonfly extermination service.  Why have your customers pay you only once when you can eliminate a beneficial insect from their yards and make a second visit (cha ching!) to take care of the problem that removing the dragonflies created?  Besides, if you only kill the dragonflies and fail to eliminate the insects that are attracting the dragonflies to your yard in the first place, you’re going to get more dragonflies coming in eventually.  If you must kill something, kill the insects the dragonflies are feeding on, not the dragonflies themselves!

Symetrum corruptum female

Variegated skimmer, Symetrum corruptum, female

I’m at a loss to understand why any pest control company would want to offer a dragonfly extermination service.  Dragonflies are not pests.  If you read my blog, you know that large swarms do sometimes form over yards on occasion, but dragonflies rarely congregate in an area without a pond or stream for more than a week.  If you wait a few days, they’ll probably move along on their own!  And even if they don’t, they can’t do anything to you or your property.  There’s just no reason to spend your hard earned money to have a pest control company kill the dragonflies in your yard – and several reasons why you should save the dragonflies instead.  I can’t help but think that this service preys on people who know little about dragonflies and sensationalizes a “problem” that isn’t a problem at all.  And why would any pest control company want to kill a beneficial insect?  I think it all comes down to making money.  What a great little scam it is to convince people to pay you kill your competition that provides its pest extermination services for free…

And now I’ll climb down from my soapbox.  I apologize if I have offended anyone and I’ll return to my regularly scheduled, less cynical, cheery posts next time!


Great news! Since I wrote this post a few days ago, the odonate community took action!  Several odonate researchers/enthusiasts teamed up, started calling people and writing e mails, and convinced the company to take down the ad for the dragonfly extermination service.  Apparently the service was offered by a Terminix subcontractor and NOT Terminix itself (though they were obviously not keeping tabs on the people they affiliate with…).  Terminix claims that they have never offered dragonfly extermination and do not intend to.  Hooray!

I’m going to leave this post up in case any other companies decide to offer this shortsighted service in the future and to address the concerns of the many people who write to me asking how to get rid of the dragonflies in their yards.  However, for now it looks like our dragonflies are safe.  Go odonates!


Unless otherwise stated, all text, images, and video are copyright © 2011

Friday 5: 5 Fantastic Insect Horror Movies

I am a huge wuss when it comes to watching horror movies.  I am jumpy in general (this might be the result of spending my early childhood in a place that has rattlesnakes in the gazillions, my current city!) so movies where things jump out really bother me.  Movies where things move in creepy ways are incredibly disturbing to me.  That scene from The Exorcist (I saw the director’s cut) where the girl crab-walks down the stairs?  Eeek!  And those horrible torture movies that are popular at the moment (Texas Chainsaw Massacre, the Saw series, etc) worm their way into my brain and stick there so I can’t think of anything else for weeks.  I really hate those movies…  However, I adore cheesy, low-budget, B-movie horror movies.  And guess which group of animals is frequently featured in these gems?  Insects!  Thus I can combine my passion for insects with my craving for bad horror movies on a reasonably regular basis.

Over the years I’ve seen dozens of insect horror movies, but there are a few that I absolutely adore.  Some are brilliant examples of classic horror films, but the others are so cheesy I laugh hysterically all the way through them no matter how many times I see them.  So, without further ado, I present my top 5 insect horror movies:

The Fly

IMDB Rating: 7.0. Image from

5. The Fly. Now many of you will be familiar with the modern version of The Fly, the one with Jeff Goldblum and Gina Davis that was released in 1986, or maybe The Fly II with Eric Stoltz.  These are both fine insect horror films.  However, if I’m going to watch The Fly, I prefer the 1956 Vincent Price version.  Vincent Price was a brilliant horror actor and really makes this movie work.  You probably all know the story: a scientist develops a teleportation device and tests it on himself.  However, he didn’t know there was a fly in the machine with him when he turned it on.  The result: the scientist’s body comes out the other side with the fly head on top!  Vincent Price’s character is a the brother of the doomed scientist and attempts to help the scientist’s wife cope with her husband’s disfiguration.  The movie is actually good, with skilled actors and a a touching plot.  The end of this movie is fabulous, but I’m not going to ruin it!  You’ll just have to watch it yourself.


IMDB Rating: 3.1. Image from

4.  Mansquito / Mosquito Man. This is a Sci-Fi Channel exclusive, and if you know anything about made-for-Sci-Fi Channel movies, you know how terrible this movie really is!  The plot is decent enough.  Once again, we have a scientist, this time a woman who is testing some new compound she’s developed on prisoners.  However, an explosion in the lab as the prisoner is about to be injected has disastrous effects!  Both the convict and the scientist begin to transform into giant mosquitoes.  And if that isn’t enough to make you want to run out and watch this tonight, let me just say that the “love” scene between mostly transformed convict and partly transformed scientist is about the most hilariously bad scene ever created for a movie.  This movie definitely falls into the so bad it’s good category, but it made me laugh.  A lot.  Hence its appearance on my list.


IMDB Rating: 2.8. Image from

3.  Skeeter. This movie follows a standard plot in insect horror movies: pollution caused by man irradiates or otherwise mutates the insects in an area (usually a remote area) and turns them into giants.  Apart from the fact that an insect this big would collapse under its own weight, I really love this particular plot.  I believe Skeeter takes place in a small town in Nevada, a town that has an illegal toxic waste dump conveniently located in a damp cave or mine shaft with a lot of water.  The mosquitoes become gigantic, about the size of a basketball, and go on a killing rampage through the area around the town.  Add to this a love story between a lawman and a woman from the town and you’ve got yourself one fabulous so bad it’s good insect horror movie!


IMDB Rating: 7.4. Image from

2.  Them! Okay, okay.  I know I should put Them! first for several reasons.  First, this movie is surprisingly detailed and correct when it comes to the science. You can actually learn something about ants watching this movie!  Second, the story is fabulous – atomic testing in New Mexico creates a hoard of ant giants that terrorize the humans who created them.  Third, this is probably THE most classic insect horror movie.  Don’t get me wrong.  Them! is a truly brilliant movie and makes for great commentary on the consequences of the nuclear age.  If I were going to recommend a good insect horror movie to someone, this would be it.  However, I just can’t put this movie above my all-time favorite insect horror movie…

Empire of the Ants

IMDB Rating: 3.2. Image from

1.  Empire of the Ants.  This movie is pure B-movie greatness!  There’s a ton of bad, overly dramatic acting.  The story is completely ludicrous.  The beginning of the movie is supposed to put the plot into context – we humans are destroying the planet, consequences be damned – but the narration is so over the top it’s impossible to take the movie seriously.  Once again, we have giant ants created due to toxic waste.  Once again, the giant ants are terrorizing people, this time a group of potential investors who are visiting a bogus land-development project headed by the scamming Joan Collins.  They have to fight off the ants to save their lives, only to get into worse and worse situations with fewer and fewer people as they go along.  The movie oozes more cheese than a big pile of nachos!  But I think it’s absolutely hilarious to watch.  Plus, the ants in this movie are actually pretty cool for the most part.  I can’t be sure, but I believe they filmed some scenes through an ant farm-like enclosure (or superimposed film of ants in such an enclosure) so that the ants crawling on the buildings and the docks look much more realistic than they do in most insect horror movies.  Still, the big showdown between the ants and the survivors at the end is so shockingly bad it can make you forget about the more redeeming qualities of this movie.  I was recently very excited (perhaps too excited!) to discover that it had been released on DVD, so you might actually be able to get your hands on a copy of this gem of an insect horror movie.  I highly recommend it.

So that’s my list.  Anyone want to share their favorite insect horror movie?  If so, leave a comment below!  I’d love to discover a new movie or two to watch!


Unless otherwise stated, all text, images, and video are copyright © 2011

Teaching 2nd Graders Science With Insects

Madagascar hissing cockroaches

Hissing cockroaches!

As in most past semesters of my graduate school existence, I’m currently earning my living by teaching.  This time around though, I’m doing something a little different.  Rather than teaching college undergrads and grads, I’m teaching undergrads and 2nd graders!

My university offers some undergraduate-led biology outreach programs.  There’s Sonoran Desert Discovery where students learn about the ecology of the desert we live in.  There’s a Marine Discovery course where students learn about marine habitats (and people give me a hard time for teaching Arizona’s students about aquatic insects!  Sheesh…).  The program I am involved with is, of course, Insect Discovery.  In all of these courses, college students learn to teach science to K-8 grade students by learning how to lead a series of age appropriate, inquiry-based science activities.  After a period of a month or so in which the undergrads are trained and practice teaching the lessons among their peers, K-8 teachers bring their classes to the university.  The undergrads enrolled in the course teach the elementary kids science by leading the inquiry-based activities that they’ve learned to teach.


One of two Insect Discovery classrooms. It's hard making a room designed for college science students work for little kids.

I’m very excited to be involved with Insect Discovery!  I first became interested in teaching by teaching entomology to kids, so it feels like I’m coming full circle.  And, this is the first time that I will be teaching other people how to teach.  This is very exciting for me!  Teaching is one of my passions and having an opportunity to train students how to do it is going to be a lot of fun – and a nice change of pace from my usual teaching responsibilities.

Let me tell you a little more how the program works.  Insect Discovery is the brain child of Dr. Kathleen Walker and she is ultimately in charge.  However, she likes to make Insect Discovery a collaborative effort each semester so that all the participants have a good experience.  She has built some measure of flexibility into the program so that the students who participate are able to teach the activities in the manner in which they feel most comfortable.

classroom decor

We tried to spruce the room up by posting a ton of drawings done by former Insect Discovery visitors.

Undergrads enroll in Insect Discovery as one of their classes for the semester.  These students are the preceptors, the ones who will be leading the bulk of the activities with the kids.  For the first quarter of the semester, they learn how to teach the kids who will visit.  We get 1st – 3rd graders in our program, thought most will be 2nd graders as a lot of their science curriculum for the year is based on insects.   The preceptors learn about insects, inquiry-based science, a little about science standards in Arizona, the general format for the activities (we offer 5 activities and the teachers choose 4), and practice teaching the activities.  After the initial training session, they jump right into teaching!  To earn their grades for the semester, they have to participate in the lectures and labs, teach the kids, observe and evaluate the teaching of their peers, and develop a new activity for the kids.  Near the end of the semester, we’ll test the new activities they’ve developed to see which ones work and which ones don’t.  The really good ones may be incorporated into the program next year.

For this class, we also have undergraduate teaching assistants.  These are students who have enrolled in Insect Discovery in the past and wanted to come back to help with the program for another semester.  They help lead the training for the preceptors, are classroom overseers when the kids are visiting, and lead activities themselves.

decomposer box

A decomposer box. This activity involves the kids digging through the dirt!

And then there’s me, the lone grad teaching assistant.  I do a bit of everything!  I’m Kathleen’s co-instructor for the course, teaching some of the activities to the students who will teach the kids.  I will teach the kids the activities myself.  I am one of the administrators of the program, an insect caretaker, and a scheduler.  I’m developing some new activities and incorporating some aquatic insects into the program.  I am the person who will be doing classroom visits to schools.  And one day a week, I will be running the program entirely by myself.  Basically, this is everything I like to do rolled into one fantastic experience: playing with insects, teaching college students, teaching K-12 students, developing curriculum, learning new things, and visiting classrooms to do outreach activities.

So what do the kids do when they visit Insect Discovery?  For one, they get to meet some real scientists, which few of them have ever done.  They’ll get to play with lots of live insects.  They’ll be guided through four of five inquiry-based science lessons.  They’ll learn about decomposers by playing in a box of dirt, petting/holding hissing cockroaches, doing an experiment to figure out what food crickets most like to eat, making observations of live butterflies in a large walk-in cage, developing their own taxonomic scheme for insects while learning about diversity, and learning about adaptations in insects.  My contribution so far has been adding a lesson about giant water bug feeding to the end of the cricket experiment so that the kids will understand that different insects eat different things.  There will be lots of insect touching, drawing, getting dirty, etc.  Basically, I would have died of happiness if I’d gotten to visit Insect Discovery as a kid, fear of insects notwithstanding!

diversity boxes

Kids doing the diversity activity will get a bunch of these boxes and play taxonomist. They'll develop a logical organizational scheme for the bugs they receive.

Because my posts are generally influenced by what I’m doing for work in any given semester, you’ll hear about Insect Discovery again.  At the very least I’m going to post some lesson plans, some for lessons that we teach the kids who come to the university and others that I am developing for classroom visits.  Many of these should be rather easy to do with kids, either at home or in a classroom setting.  For the teachers who read my blog, feel free to poach these ideas as all good teachers do!  I’ll also likely describe how to care for some of the insects we use in the program.  Should be a fun semester – and I’m finally going to get to work on my long-standing goal of posting some lesson plans on my blog!  I hope you’ll enjoy the posts!


Unless otherwise stated, all text, images, and video are copyright © 2011

Friday 5: 5 Places I’ve Found Booklice in My House

Ah, booklice.  They’re tiny insects many people have never seen.  They eat really random things like the paste in books and certain parts of dry tree branches, dead skin cells.  Some species get into grain storage areas and munch away happily for ages.  I seem to find a lot of them in my house.  Don’t know why exactly, but they make an appearance often.  Today’s Friday 5 will highlight 5 places I’ve found booklice in my house!



My flour canister. I opened my flour canister to make a cake one day and noticed the top of the flour was moving.  I have a freakish ability to see very, very small things moving around (remind me to tell you about the mite incident at the vet!), but even I was surprised I noticed them!  There were hundreds, if not thousands.  I chucked the flour – and didn’t get cake.  :(  On bright side, my students got to see live psocopterans in lab.  That’s always a good thing!



My gerbil food container. I love rodents.  I’ve had a rodent or a hedgehog since I was about 12 years old.  My most recent rodents have been gerbils, so I have gerbil food.  And once, it was infested with booklice.  Lots and lots and lots of booklice.  I’m sure my gerbils wouldn’t have cared, but my husband did, so into the trash it went!

Okay, two grains in a row.  Let’s move on to the more bizarre things I’ve found booklice on!



My aspen tree log. When I moved from Colorado to Arizona, it was the first time I had been far from my family.  Heck, I even went to college 7 miles from home!  The house where I lived in Colorado Springs had this awful little aspen tree in the front yard.  It was always a little diseased, so it was stumpy the entire 20 years my dad lived in that house.  Still, it reminded me of home.  When he cut a big dead part off the tree, I took one of the logs back to AZ with me and set it on my dresser so I had a little piece of home.  A few years later, I noticed  insects crawling all over it.  It too was relegated to the trash can, but I didn’t miss it.  I didn’t need it to remind me of home anymore.  Now I content myself with photos of that sad little aspen tree.  That really was a terrible tree.


paper bouquet

My paper flowers. I had a DIY wedding.  Among the many decorations that I made for the wedding were bouquets of paper flowers, made from a giant roll of parchment that featured prominently in my childhood.  After the wedding, I set a few of the bouquets on a bookshelf in my living room.  8 months later, I was dusting the things on the shelf and noticed that one of the bouquets was crawling with booklice!  The other bouquet, 12 inches away, was 100% booklice free.  Strange!  I took some photos (the booklouse at the top of this post is compliments of my paper flowers) and intended to clean them off, but I got distracted and forgot.  When I went back to clean them a few days later they were gone.  Lord knows where they went, but I suspect they made their way into one of my husband’s many tasty board games on the shelves below.  :)




Jorge. Tucson has this AMAZING Day of the Dead parade called the All Soul’s Procession.  A couple thousand people dress up in insanely creative costumes and wander through the hippie district and downtown areas celebrating life and death.  Anyone can join in and some people make these elaborate and/or gigantic altars, puppets, or costumes from all manner of media.  I walked for several years before I decided it was time to jazz up my costume with a puppet.  Thus, Jorge was born.  I spent weeks working on him, paper macheing him with care.  I carried him in two parades before he found a home on my bedroom wall.  (Yes, I spent several years sharing a room with a creepy, 4-foot tall skeleton puppet.  What of it?)  I loved Jorge.  I was so disappointed when I found him infested with booklice.  It was a sad day when Jorge was retired from his honored place on the wall, interred in the trashcan, and replaced with more normal decor.

So there you have it!  5 places I’ve found booklice in my home.  Has anyone else found booklice in their homes?  If so, I’d love to hear where you found them, so leave a comment below!

Addendum (October 15, 2016): A lot of people have found support for their extreme fear or disgust of these insects by talking to other people in the comments section of this post. By all means please continue to do so! I am adding this little note to state this: I will approve your comments so they’ll be visible to everyone else, but I am not going to respond to your comments myself.  I choose not to because, to me, these little insects are merely a minor nuisance and I do not feel that I am a good resource for how to deal with your concerns. There are other people here who will give you the support you seek. That said, please also note that I will not tolerate any offensive, insulting, or otherwise malicious comments here.  Just don’t go there.


Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Mayflies, Damselflies, and Stoneflies: What’s the Difference?

I haven’t done an identification post for a while, so its high time that I write another one!  I find that a lot of people have a hard time distinguishing the aquatic insect nymphs with tails sticking off the back, the mayflies, the damselflies, and the stoneflies.  They’re easy to tell apart once you learn a few basics!  A lot of people have read my post on how to tell the damselflies and dragonflies apart as nymphs, so let’s start with them.

Behold, the mighty damselfly:

damselfly nymph

Damselfly nymph

There are several things to look for that will let you know this is a damselfly nymph and not a stonefly or mayfly.  However, the mouthpart is a dead giveaway!  If you don’t know about the awesome odonate mouthpart, allow me to enlighten you.  Odonates have highly adapted mouthparts that form a long, hinged structure that they can thrust out toward prey to capture it and draw it back to the chewing mouthparts to be eaten.  There are pictures of this structure available on the post linked above and you can see a little part of it sticking out past the head of the damselfly in the image above.  Odonates are the only insects that have this style of mouthpart, so if you have a nymph with tails sticking off the back-end and you can see a long, folded mouthpart under the head, you’re looking at a damselfly for sure.

But perhaps you’re looking at an insect in the water and you aren’t able (or willing) to pull it out to look at the mouthpart – what then?  Well, take a look at the location and structure of the gills:

Damselfly gills

Damselfly gills

The three damselfly “tails” are really gills that they use to help them breathe and swim!  They are always located at the back-end of the insect and they tend to be broad and leaf-shaped with varying levels of pointy-ness.  As you’ll see in a moment, the stoneflies and the mayflies have gills in other locations and do not have broad, leaf-like tails.  If you see gills that look like the image above, you’re looking at a damselfly nymph!

Let’s move along to the mayflies:



You should notice some differences between the mayfly and the damselfly right away.  First, look at the tails:

mayfly tails

Mayfly tails

Nothing broad and leaf-like about these tails!  Mayflies have long, filamentous tails, often longer than their bodies.  They also usually have three tails like the damselflies, but some groups only have 2.  Clearly, the flat-headed mayfly in the photo falls into the latter category.  This causes some confusion when distinguishing the mayflies from the stoneflies, as you’ll see in a moment.  However, if you see 3 filamentous tails, you’ve got a mayfly on your hands!

Now let’s take a look at the location of mayfly gills:

mayfly gills

Mayfly gills

The gills  are always attached along the sides or the bottom of the abdomen in the mayflies, never on the thorax or sticking off the back. If you see gills in another location, you’re not looking at a mayfly.  Mayfly gills tend to be broad and leaf-like as in the damselflies, though they may be fringed or sharply pointed in some groups.  They usually have a pair of gills on nearly every abdominal segment, though the exact placement on the abdomen varies by group.

Now we’re left with the stoneflies:



Stoneflies and mayflies look a lot alike in most cases.  The mayfly in my photos above is a specialized species adapted for living in fast flowing water, but a lot of mayflies are shaped more like the stonefly depicted here.  How do you tell them apart when the body shapes are similar?  Let’s look at the tails first:

Stonefly "tails"

Stonefly "tails"

Stoneflies always have two tails.  Like the mayflies, they’re long and filamentous.  In some species, these tails are very long.  In others, they’re shorter than the length of the abdomen.  They’re never leaf-like.

Let’s check out the location of the gills too.

Stonefly armpit gills

Stonefly gill location

Unlike the damselflies and mayflies, stonefly gill placement is quite variable.  Many species don’t have gills.  Some species that do have gills don’t get them until they’ve matured to some specific point.  Some species have gills on the abdomen, but if they do they’re located only on the first few abdominal segments and never further down.  (This helps distinguish them from the mayflies, which almost always have gills on the 3rd-6th abdominal segments.)  But in most stoneflies with gills, you’ll find them in their armpits, as indicated in the photo.  Stonefly gills are very different from the broad, flattened gills of damselflies and mayflies.  They typically have a round main stalk with multiple branches.  These are called “finger-like” gills for some reason, but I think the structure is rather similar to the boojum tree, just on a smaller scale:

Boojum Tree

Boojum Tree. Photo by Bernard Gagnon, from wiki/File:Boojum_Tree.jpg.

I find that people have the most trouble telling the mayflies and stoneflies apart.  If the mayfly has three tails, no problem!  It’s a mayfly for sure.  However, you have to remember those pesky two-tailed mayflies that throw a wrench in the whole system.  Plus, mayflies are notorious for losing their gills.  If you’re working with preserved specimens, sometimes it’s hard to figure out where the gills did or did not attach.  How then do you tell a two-tailed mayfly with no gills apart from a similarly shaped stonefly with no gills?  It’s easy!  Look at the claws on the legs.  Mayflies have one claw on every foot.  Stoneflies have two.  It couldn’t be simpler.

As with any identification, the more animals you see, the easier this gets.  For those of you who have little experience collecting and identifying insects, getting a specimen IDed to order can be a challenge at times!  Remembering the characteristics of tons of insects can be hard too.  I thus present this handy-dandy chart that summarizes the information I covered above:

Mayfly Damselfly Stonefly
Location of Gills abdomen end of abdomen when present, thorax, base of abdomen
Shape of Gills leaf-like, plate-like, or fringed leaf-like finger-like
Style of Mouthparts chewing chewing + hinged segment folded under head chewing
Number of Tails 2-3 3 2
Shape of Tails filamentous leaf-like filamentous
Number of Claws 1 2 2

If you forget the characteristics of the mayflies, damselflies, and stoneflies, use this chart as a quick reminder of what to look for!

Next up: another thrilling edition of Friday 5!  This week’s will feature 5 places I’ve found a particular type of tiny insect in my home.  Check it out to discover where these little beasts may be lurking!


Unless otherwise stated, all text, images, and video are copyright © 2011

Friday 5: Arizona’s Amazing Aquatic Beetles

My post Arizona’s Amazing Beetles proved to be quite popular.  Today I’m going to do a similar post, but this time I’ll focus on some of the aquatic beetles in my state.  Arizona has some pretty impressive aquatic insects and the beetles are no exception!  A lot of Arizona’s aquatic beetles are found in other states, but they are things I associate with my home and are therefore going on my list today.  These are 5 of my favorites:

Dineutus sublineatus

Dineutus sublineatus, a whirligig beetle.


Whirligig beetle, Dineutus sublineatus (Gyrinidae).

I adore whirligig beetles!  If you’ve never had an opportunity to see these beetles in action, you’re really missing out.  I recommend you go to your nearest stream, find a calm pooled area, and look for them ASAP!  Whirligigs zig and zag and spin and otherwise move frenetically across the surface of the water.  They’re also gregarious, so you usually find a whole bunch of these beetles in one place, whirling and spinning in big groups.  The behaviors are interesting, but the structure of these beetles is just as great.  The hind two pairs of legs are very short and broad and act like little oars to propel the beetle across the surface of the water or underwater when they dive.  Also, these beetles have 4 eyes, one pair looking up into the air and one pair looking down into the water!  I like this species of whirligig best partly because it’s big (close to 3/4 inch!), but also for the gorgeous iridescent green and bronze colors that you can see when the light’s right.

Thermonectus marmoratus

Sunburst beetle, Thermonectus marmoratus


Sunburst beetle, Thermonectus marmoratus (Dytiscidae)

I talked about these beetles in my first Arizona beetle post, but they’re just so pretty I can’t help myself.  I could watch these beetles swim for hours.  They’re quite possibly the most graceful swimmers of any animal I’ve ever seen.  That is, until they find prey, hunt it down, and rip it to shreds with their powerful mouthparts!

Postelichus sp

Long toed water beetle, Postelichus sp


Long toed water beetle, Postelichus sp (Dryopidae)

I don’t know what it is exactly that makes me love these beetles so much.  They’re fairly small (1/4 inch long or less) black beetles.  They have about the coolest antennae of any insect, though they keep them tucked down into a groove in their heads so they’re hard to see.  They’re heads are normally partly embedded in their thoraxes (picture the head in the photo retracted to the back of the eyes), which gives them this funky stubby look.  The larvae of aquatic dryopid species are terrestrial, which is completely backwards for aquatic insects.  These are really cool little beetles!  I get a little giddy every time I find them.  Plus, they are a clean, flowing water species so you can find these beetles in some of the most beautiful areas of Arizona.  Look for them in riffle areas in streams.

Peltodytes sp.

Crawling water beetle, Peltodytes sp.


Crawling water beetle, Peltodytes sp. (Haliplidae)

These beetles have been right up at the top of my list of favorite insects from the moment I caught my first.  Honestly, I like them because they are funky looking little beetles.  They’re tiny, less than 1/8th inch (hence the less than perfect photo – my 105mm macro lens isn’t quite up to the task of photographing haliplids!).  They’ve got big, broad shoulders and heart-shaped elytra, but then they have these itty bitty little heads sticking off the front.  They’re miserable swimmers, so they prefer to walk and get their common name from this habit.  And if you flip them upside down, you’ll see a really cool structure.  The first segment of the hind legs, called the coxa, is enormous on these beetles!  They expand into big plates that cover nearly the entire underside of the abdomen
(check out this photo to see it).  The scrawny little hind legs then peek out from under these giant plates so that you can’t see the first few leg joints.  As I said, funky looking beetles!  Like the long toed water beetles, I find these beetles in clean, flowing water in many parts of Arizona.

Hydrophilus triangularis

Giant water scavenger beetle, Hydrophilus triangularis

Giant water scavenger beetle, Hydrophilus triangularis (Hydrophilidae)


These beetles are awe-inspiring.  They’re huge, over an inch long.  They’re sleek, beautiful black with just a hint of green under the right conditions.  In Arizona you find them in murky ponds, so you’ll see these large black things emerge into the light for a moment as they get air before they disappear back into the water.  They have a massive spike used for defense that runs down the center of the thorax and ends midway down the abdomen in a vicious looking point.  Their larvae are gigantic, close to 3 inches long.  They move into the muck along the shoreline when they near pupation and emerge occasionally as mud-covered monsters with massive jaws.  And for all this impressiveness, they’re herbivores as adults, contenting themselves with eating plants in vegetation-filled ponds.  Love ’em!

So those are 5 of my favorite aquatic beetles found in Arizona.  I normally would have included the water pennies, but I’ve already discussed them twice and didn’t think I should keep beating that dead horse.  If you have a favorite aquatic beetle, I’d love to hear what it is!  Leave a comment below!


Unless otherwise stated, all text, images, and video are copyright © 2011

Behavioral Responses of Damselflies to Storms

Fountain Creek Park

The pond where I did my research at Fountain Creek Regional Park, CO.

Last week I talked a bit about how weather affects odonate behavior, my favorite topic in biology. Today I’ll go over the study I did to look at these weather related behaviors more closely. Like the little study I did that focused on damselflies and weather in my first college ecology class, this study was done at the wetlands in Fountain Creek Regional Park outside Colorado Springs, CO.  This research was actually part of my undergrad senior thesis!

pond at Fountain Creek Park

My study site. It extended from the cattails on the left side out to the end of the log in the water and from the dock (not visible) to just beyond the log.

I had to work the summer I collected my data, but I went to the wetland most days after work and recorded observations from 4-5PM.  I plopped down on the dock with all of my weather measuring equipment and watched the damselflies in a 5.5 square meter area along the edge of the pond for an hour.  I divided the hour into 5-minute periods and recorded weather data (wind speed and direction, temperature, light intensity, barometric pressure, relative humidity, and whether it was raining or not) for the first minute of each period.  I then spent the remaining 4 minutes counting the number of damselflies that flew within my study area.  Part of that area was filled with cattails and the rest was over open water as you can see in the photo.

Having spent 14 years of my life in Colorado Springs, I can tell you one thing with certainty: in the summer it rains nearly every day between 4 and 5PM.  This meant that I was out watching damselflies during the exact time the storms were blasting over Pike’s Peak and ripping across the plains.  I would sit there watching these phenomenal storm clouds rolling straight toward me with fantastic speed.  Guess who got rained on A LOT that summer?  Me!  I also got hailed on, was sandblasted in high winds, and was once driven running the half mile back to my car when the lightning got a little too close.  However, the clouds moved so quickly (they have to build up a ton of momentum to make it over Pike’s Peak’s 14,115 feet!), the storms didn’t last long, usually 30 minutes at most.  During that time, the weather would transform from hot, sunny, and still to cold, windy, and rainy in the span of a few minutes.  It would usually rain, sometimes very hard, for 10 minutes or so.  Then the storm would suddenly be over and it would become sunny, warm, and still again.  This whole series of events would take place during my hour at the pond.

Now most sane people go inside during storms.  Rain in Colorado is incredibly cold and the storms can be quite powerful with a lot of lightning.  Call me crazy, but I loved curling my whole body into my enormous rain jacket and getting rained on.  I was rewarded for my insanity too because I got to see some things that very few odonate people get to see.

First, I learned that there was a rather distinct pattern of behaviors that was associated with the weather patterns I observed.  The damselflies were most active in sunny, warm, still conditions, the typical weather central Colorado experiences during the summer.  They flew readily into and out of my study area, hunting, looking for mates, mating, and laying eggs.  As soon as a storm approached, you’d see some pretty interesting things.  As the clouds moved in and it became darker and cooler, the number of flights the damselflies made decreased so that fewer individuals flew during a counting period.  As the wind picked up, the activity decreased even further.  Flight activity ceased altogether if it started to rain.  Of all the many hours I spent at the pond, I saw only a single damselfly flying while it was raining, and it was during a very light rain when the sun was still shining.  Most interestingly to me, the damselflies would start to leave the pond when the weather deteriorated sufficiently.  They were displaying pond abandonment behavior.  However, as soon as the storm was over and the sun came back out, the damselflies would return to the pond and resume their normal activity as if nothing had happened at all.  It was fascinating and I am so happy I got to see this behavior!

pond at Fountain Creek Park

My pond at Fountain Creek Park during a light storm.

The flight activity of the damselflies at Fountain Creek Regional Park was clearly affected by the weather, but I was interested in knowing which of the seven weather parameters I measured were contributing to the flight activity I observed.  I used a statistical procedure (multiple regression for those interested) to determine that light intensity, temperature, wind speed (but not direction), and whether it was raining or not were the weather parameters most closely associated with the flight activity that I recorded.  Of these, light intensity showed the greatest association, followed closely by temperature.  Essentially, the brighter and warmer it was, the more damselfly flights you see.

(Brief aside: Remember how I said last time that I didn’t agree with that Russian scientist who thought that barometric pressure was a major player in shaping odonate behavior?  My results didn’t indicate that barometric pressure had any effect.  This coupled with the fact that the Russian didn’t even measure barometric pressure in his study makes me skeptical of his results.)

So four weather parameters were important.  The statistical test confirmed what I’d observed visually, that damselflies flew more readily in good weather than in poor weather.  “Good” conditions were warm and sunny with little or no wind while “bad” conditions were cold, rainy, windy, and dark.  I definitely observed pond abandonment behavior.

The most important question is this: what does all this mean?  I think my data suggest two things:

pond at Fountain Creek Park

My pond at Fountain Creek Park, right after a storm.

1) The damselflies might be able to pick up on cues in the changing weather that alert them that a storm is approaching.  Think about a damselfly, those big wings on a scrawny little body.  If you’re a damselfly, it could be physically dangerous for you to be out in a storm.  Being blown into the vegetation or the water could be deadly, heavy raindrops could impart a significant blow, and evaporative cooling could cause your body to cool down so fast that you can’t escape if the weather gets worse.  Better to leave the pond before a storm than risk getting caught exposed in one.  I think storms are dangerous to odonates, so the pond abandonment behavior that has been so often reported might be a means of protecting them from harm during bad weather.

2) Pond abandonment behavior might be related to roosting behaviors.  Consider these ideas: Damselflies roost in sheltered areas away from the water at night.  Storms usually result in a drop in the light level and temperature, which are the same things that happen as it gets dark at night.  Damselflies disappear from the water before it starts to rain.  It is therefore quite possible that pond abandonment behavior and simple roosting behaviors might be the same thing: odonates returning to their overnight roosts when it gets dark and cools down.  It is likely also advantageous for damselflies to seek shelter during storms, but this could be a secondary benefit, something they gain by completing a behavior that has nothing to do with protecting them from storms.

Are odonates using weather cues to abandon ponds before storms?  Or are they simply returning to their roosts because it’s getting dark?  Are storms dangerous to odonates?  These are some of the endless new questions I had after I finished this project and would like to answer.  I had intended to study this behavior in more depth in grad school, but then I decided to attend grad school in Arizona.  Colorado’s clockwork storms are perfect for studying these behaviors.  Arizona’s wildly unpredictable storms are not.  So, I changed my focus to the water bugs and have studied them ever since.  I will go back to my beloved odonates someday though!  I also decided a while back that my damselfly study was actually pretty unique and could make a real contribution to the scientific literature on odonates.  Ten years after I wrote my undergraduate senior thesis, my data was published.  If you’d like to read more about my study, look at some pretty graphs and whatnot, the citation is listed below.

I am dealing with some heavy things in my personal life at the moment, so I have no idea what I’ll do for the next few posts.  I’m going to let myself be driven by whims for a week or two.  I hope you’ll all check back to see where my whims take me!

Paper citation:

Goforth, C. L.  2010.  Behavioural responses of Enallagma to changes in weather (Zygoptera: Coenagrionidae).  Odonatologica 39: 225-234.


Unless otherwise stated, all text, images, and video are copyright © 2011