Where to look for dragonfly identification information

A lot of the people who have sent me dragonfly swarm reports have expressed an interest in identifying the dragonflies they’re seeing in their yards.  I think this warrants a post on where to find information about dragonfly identification!  Today I’ll cover some of the books I really love and some of the best online resources you can use.  I’ll also tell you what you can do if you’re stuck and need the advice of an expert to help you figure out the dragonflies that you’ve seen.  I’m a scientist, so I have a lot of technical books that I can use to help me identify dragonfly species very precisely using a microscope and other special tools, but this post is meant to help people who are not dragonfly experts to find accessible information.  I hope you will find this useful!

Dragonflies Through Binoculars cover

I am a huge book lover, so I personally turn to books whenever I want to ID a dragonfly or damselfly that I’ve seen.  I have several favorites, but I use two over and over again because they are so thorough and include ALL of the species in a particular area.  Dragonflies Through Binoculars by Sidney Dunkle is a great source of information about the North American dragonflies.  It includes photos, descriptions, distribution maps, and flight dates for each of the species.  It also does a great job of highlighting the distinguishing characteristics so you can tell species apart even if they are very similar in appearance.  This is a great book and I always take it with me when I travel.  The only downsides are that the book doesn’t include the damselflies and it it now 10 years old, so some of the information might be slightly out of date.  The book I turn to again and again when I want to have all of the dragonflies and damselflies in one place is Dragonflies and Damselflies of the West by Dennis Paulson.  This book shares all of the great features of Dunkle’s book, but it is is newer and includes the damselflies.  I LOVE the behavioral information in this book!  However, if you live outside of the western part of the US and Canada, this book isn’t going to be as useful.   Luckily, dragonflies are popular, so there are a lot of great resources out there!  Your best bet is getting on Amazon and searching for either dragonfly or odonata and your state or country.  There are tons of local guides available, so it’s definitely worth looking for one for your area!

odonata central screen capture

There are several great online resources, but I am particularly fond of Odonata Central.  Odonata Central is an amazing website!  It include up-to-date information about flight seasons, distributions, characteristics, etc.  Even if you know nothing about the dragonflies you’re seeing, Odonata Central is an excellent resource.  For example, to see a list of every species in your area, you can click on the checklist link at the top of the page.  The website will guide you to your location (in the US, you can get information for your county) and a list of all of the species in your area will appear.  You’ll also see links for photos, maps, and information about each species on the list.  By clicking through the images and reading the descriptions, you will likely be able to identify the species in your area.  The best part: this works for almost any location, including areas outside of North America.

Many, many people (including Odonata Central) have photo galleries of dragonflies online and simply scrolling through photos can take you a long way toward identifying the species you see in your area.  I love the Digital Dragonfly website’s image gallery, though not all American species are included.  Because I live in southern Arizona, I also frequently check websites such as Arizona Odonates and California Dragonflies and Damselflies for photos and identification information.   To find websites with information about your local dragonflies and damselflies, check out the links page at Ode News or the links page at Odonata Central.  They both have comprehensive lists of good, reliable information available online.

Bug Guide screen capture

If, after you have tried the field guides and scrolled through photo galleries, you just can’t decide whether your dragonfly is a neon skimmer or a flame skimmer, where can you turn?  There are two great resources available at your disposal.  The first is BugGuide.  In addition to great photo galleries, you can also submit photos of dragonflies or damselflies and request an ID.  Bug Guide is a network of insect and spider enthusiasts who volunteer their time helping people ID bugs they’ve seen.  When you submit an ID request, one of the many Bug Guide users will likely know which species you’ve seen an give you an ID!  To get the most specific response, take a photo of at least the back and the side of the dragonfly or damselfly as clearly as you can because the characteristics that distinguish species are most often in these areas.  Then upload your photos to the Bug Guide by clicking ID Request at the top of the page and following the instructions.  Most people get responses to their inquiries within a few days.

Did you know that there are entomologists all over the US trained to help non-entomologists identify insects?  Land grant universities are often required to maintain research collections of various groups of organisms (including insects, snakes, fish, crustaceans, plants, etc) and to provide outreach to the public.  If you have a land grant university in your area, you likely have someone who can help you ID insects and provide information about them at the university.   The Cooperative Extension service is the main outreach component of most land grant universities and nearly every county in the US has an office.  The Cooperative Extension service employs a large number of entomologists, so give your county office a call!  If your county’s entomologist can’t ID a dragonfly for you, he or she likely knows a person who can.  And finally, Odonata Central maintains a member directory that includes many dragonfly experts and/or enthusiasts around the world.  If you click on View All at the top of the page and search for your location, you might be able to find a odonatologist nearby who can answer your dragonfly ID questions and give you more information about your local species.  That said, tracking down their contact info might not be easy in every case.

As I said earlier, dragonflies are very popular insects, so there are tons of resources available!  In fact, the volume of information available can be overwhelming if you don’t know where to begin.  Hopefully, this post will direct you to the best resources available and make it as easy as possible to figure out which dragonfly species you’ve been seeing.  Good luck!

I’m getting away from dragonflies for the next few posts, but check back near the end of October for a summary of the results of my dragonfly swarm data collection effort this summer.  I’ve collected more reports than I ever thought I would, so it should be an interesting read!


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Damselflies and Antlions – What’s the Difference?

I get a lot of questions about insects when people learn that I’m an entomologist.  These frequently sound something like, “I saw this little brown beetle in my house the other day – what is it?”  Most of the time, I have a hard time identifying an insect based on a description like this.  You often need to see an insect to properly identify it.  At the very least you need a photo.  There are, after all, close to a million known species of insects and there may be over 10,000,000 insect species in all!  One person can’t possibly know all of the species of insects, no matter how great their memory is.  However, there are some things that I can identify based entirely on a quick and dirty description.  One of the easiest is the difference between a damselfly and an antlion.  They look very similar so I completely understand why people have a hard time telling them apart, but there are some obvious distinctions if you know what to look for.

First, let’s take a look at a damselfly:

damselfly adult

Damselfly adult

This is a member of the family Coenagrionidae, so it is one of the very common little blue damselflies you’ll see around ponds.  What do you notice about the structure of this insect?  Look closely at the wings.  Click on the image to enlarge it if you need to.  How many wing veins and cells in the wings do you see?  The wing veins are the lines on the wings while the cells are the little open square parts between the wing veins.  The color on damselflies is often distinctive.  They fade badly once they are dead, but this damselfly used to be a brilliant blue.  Now look at the head.  Do you see any antennae?  Probably not.  They’re visible (there’s one sticking off the right side of the head right above the right eye, looks like a little hair or a piece of dust), but they’re small, bristly things that most people wouldn’t even notice.  They’re definitely shorter than the length of the head.

Now look at the antlion:



Can you see why people get these two insects mixed up?  Even some beginning entomologists have a hard time telling the two of these apart!  Look closely at this insect like you did with the damselfly.  First, you should note the color.  This insect is brown, as are almost all antlions.  While some damseflies are brown (especially females), there are many that are brightly colored.  If you have a brightly colored individual with this shape, it’s a damselfly, not an antlion.  Next, look at the wings and observe how many cells there are.  How many do you see?  Antlions belong to the order Neuroptera, the net-winged insects.  Antlions, like other neuropterans, have tiny cells in their wings and a whole lot of them, many more than you’d ever see in a damselfly.  If you see an insect with this shape with tons of little cells instead of 100 or so large, open cells, you’re looking at an antlion.  But the easiest way to tell them apart is by looking at the head.  What do the antennae look like on this insect?  They’re very long, much longer than then length of the head, and thick.  In other words, they’re quite conspicuous, very unlike the tiny, bristly antennae you can barely see in the damselflies.  If you see an insect with this shape that has long, luxurious antennae, it’s antlion.  If it has antennae that are barely visible, it’s a damselfly.  Easy, right?

Of course, there’s one other obvious distinction.  Damseflies are diurnal, which means that they are active during the day.  Antlions are nocturnal, so they are active at night.  You might occasionally find an antlion out during the day, but it’s very unlikely to see a damselfly at night.  Most of the time it’s easy to tell these two insects apart based solely on when you see them!  But, it’s always good to check the length of the antennae and the number of wing veins to be sure.

Now that you know the difference between an antlion and a damselfly, you might start noticing how often these two insects are mixed up.  There is a tank top that I would dearly love to have that depicts an antlion.  The people selling it have it labeled as a dragonfly (not even a damselfly!).  Rubber stamps, especially ones based on old engravings from the 1800’s or early 1900’s, often erroneously depict antlions when they’re supposed to be damselflies.  And all sorts of people feel the need to put antennae on dragonfly and damselfly images.  I don’t know why this is so common, but you will see dragonflies and damselflies with long curly antennae everywhere you look.  This is actually my single biggest pet peeve as an entomologist.  I couldn’t care less about using the word bug when you should use insect, but stick antennae on my favorite insects and you and I are going to have words!

Next time I’ll likely post about how to tell damselfly nymphs apart from stone fly and mayfly nymphs.  They’re easy too, so I hope you’ll check in again soon!


Text copyright © 2010 DragonflyWoman.wordpress.com