learning to i.d. butterflies, with dr. jeffrey glassberg

WE SPEAK OF butterfly plants and of making butterfly gardens, but how well do we really know the diversity of butterfly species that might visit those offerings? Butterflies, and especially how to sharpen our ID skills and become keener butterfly-watchers, were the topic of my recent chat with Dr. Jeffrey Glassberg, author of “A Swift Guide to Butterflies of North America,” among other books.

Glassberg is President of the North American Butterfly Association, and an adjunct professor in the Department of Ecology and Evolutionary Biology at Rice University.

Plus: Comment in the box at the bottom of the page to enter to win a copy of the updated butterfly guide, to learn to identify butterflies like the two variable checkerspots at the top of the page.

Read along as you listen to the May 7, 2018 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

butterfly i.d. skills, with dr. jeffrey glassberg


Q. I’m so enjoying the book. Actually, this is my second edition of the book, as it is yours.

A. Oh, good. Thank you so much for having me.

Q. Yes. So, The Swift Guide is meant to support us in learning to recognize butterflies, and so it’s highly visual. It’s kind of different from other guides. Want to tell us a little bit about your approach?

A. Sure. So, when I’ve written books over the years, I try to ask, “What is the purpose of this book? What is it trying to do?” And then I try to do everything I can to make it the best for that purpose that I can. And the purpose of this book is to let you identify butterflies, to recognize what the butterfly that you’re seeing in your garden, or out in the woods or the meadows near your house, what kind of butterfly is it? So, rather than having long wordy treatises on this and that, it focuses on what the butterfly looks like and carefully having arrows that point to the important things that distinguish it from close relatives, and then right there at the arrow telling you what to look for.

And then it of course gives information that’s relevant to identifying it, for example, the time of year it flies, the range where it flies. So if there’s a butterfly that’s only found in Florida and you’re in California, it’s not likely to be that one.

Q. [Laughter.]

A. So that’s relevant to identifying it. Or, if I say it only flies in the early spring and it’s now the middle of the summer, it’s not likely to be that one. We tell what the butterfly uses as its caterpillar food plant and that helps reinforce if you find it flying around this plant that is its food plant, then maybe it’s more likely that’s what it is, kind of thing.

Q. Yes. And the images of the butterflies are butterflies photographed alive on plants, not silhouettes like in many field guides, these disembodied sort of creatures on a white background or whatever.

A. That’s right. And I think that’s also useful because you get a better feel about what the butterfly really looks like in the wild, and what it might be on, and how it holds itself. So that’s all relevant, again to trying to identify it.

Q. Yes. And I have to confess that I spend a lot of time when I see something that I don’t recognize right away in the garden. I go right to the back of the book, to the visual index [above]. I don’t know … is that cheating? [Laughter.] But I use it a lot.

A. No, not at all. And I’m glad. Everybody approaches things differently, and so my experience has been, there’s a pretty significant percentage of people—I’m not sure exactly what it is, a third or a half—who for example find, as you do, the visual index very useful. It gets you to the right area in the book. Whereas,other people, they don’t use it at all. And so, I try to make it so that different kinds of people can still use it well.

Q. And so if people don’t know what we’re talking about, it’s little thumbnail-sized, gridded-out thumbnail-sized pictures, there’s several pages of them, and so you can visually scan these two or three pages of these little icons, these little thumbnails, and you go, “It kind of looks like that,” and then you can go to page 207 or whatever, and see, in fact, if that’s who you’ve seen.

I just find that really helpful and less overwhelming.

So, of course the book is divided sort of taxonomically, like the world of butterflies, into six families. I think a lot of lay people like myself, especially a lot of gardeners would say, “Oh, swallowtails, there’s lots and lots of swallowtails,” but that’s the smallest section, isn’t it? [Laughter.]

A. Yes. There are many species of swallowtails on the planet, still less than some others, but quite a few. But in most areas of the United States there aren’t that many species of swallowtails, but because there the largest in size, among the families of butterflies ,and most of the individuals tend to be large, they’re the butterflies that people notice the most. [Above, from the book, one page in the swallowtail family section.]

So, if you’ve got tiger swallowtails flying around your house or giant swallowtails, they’re pretty big butterflies, and they’re hard to not see. Whereas if you have hairstreaks or skippers flying around your house, most people would frankly, would never even notice them. But when you do notice them, if you look at them, get a good look at them, which you can easily, they’re amazingly beautiful. So looking at butterflies closely, small ones, opens up a whole new world to you.

Q. So there’s five other families. One, I think is the section that was biggest were the brushfoots. Again, I know some Commas and some crescents and some fritillaries and some checkerspots that I’ve seen, but I didn’t know they were in that family. That’s another thing that you learn by seeing them with their associated family.

A. Yes. I think the brushfoot family is maybe the least coherent assemblage of any of the others. If it’s not a swallowtail and it’s not a gossamer-winged butterfly, and it’s not a skipper and so forth, then it’s likely to be a brushfoot.

And the other thing about them is the majority of them, not all of them, but the majority of them tend to be an orangey-brown color. So if you think of a monarch, it’s a kind of brushfoot, or if you think of a paintedl or an American lady, those are brushfoots. So they tend to be orangey-brown and as I say that’s not true of them all. But they’re more varied in terms of size and color than the other groups in North America.

I mean, if you look at the rest of the world, the metalmarks, which there are very few of in North America, in South America they’re unbelievable numerous and varied in every possible way.

Q. One of the other families are the whites and yellows. And so that, of course made me think of my Brassica crops and how I love the cabbage white butterfly [laughter], whose caterpillars like to eat Brassicas. Now that’s a non-native butterfly species, correct?

A. Yes, that’s one of only a couple of-

Q. That’s what I was going to ask. Yes, because most of the book would be native—most of our butterfly species would be native, yes?

A. Almost everything in there … there’s only really, I think … well, now it’s up to three in the United States outside of Hawaii. Hawaii has quite a number of non-native established butterflies. But in the rest of the U.S … there’s only two in the U.S. and an additional one in Canada. There’s the Cabbage White and there’s a butterfly called the European skipper [above]. And now, just a few years ago, another butterfly called common blue has become established in Southern Canada and will probably soon enter the United States, if it hasn’t already.

Q. So, if we were to sort of right now, together virtually, if you were going to take me butterfly watching here out loud, should I get my binoculars? Like, what should I do? What’s going to equip me to be a better observer? Because they move fast, they’re small, and frequently they catch our eye from a distance. How do we do this?

A. So, you want binoculars. Ideally, you want binoculars that are close-focusing binoculars, and by that I mean binoculars that when the object, in this case a butterfly, that you’re looking at is, let’s say only 5feet away from you, that your binoculars can focus on it sharply. Most binoculars are built to look far away.

Q. Yes.

A. And so if you get closer than 20 feet or certainly 10 feet, most binoculars won’t be able to focus on them. It’ll be all blurry. But because butterflies you can approach very closely, and you will normally be close to them, you want binoculars that, as I say, certainly focus less than 6 feet, and some go down to almost 3 feet. So you’ll want binoculars.

Many, many people that are into butterflies photograph them, because it’s really so easy to do. You can use something as commonly available as your cell phone, but fairly inexpensive point-and-shoot cameras work awfully well for many butterflies.

And then of course, you can use very expensive cameras if that’s what you want to use also. The other thing you probably want to do is, if you’re going to go out into the field as opposed to your own garden, you want to dress appropriately, and you want to do things like tuck your pants into your socks so you don’t get things crawling up on you, or you want to wear a hat to keep the sun off you. So, there’s certain things you want to do.

Q. So, in a bird book the ornithologist Pete Dunne, he says something like, “Birds are almost always where they’re supposed to be.” And in your book, in the Swift Guide, with each species entry, you have little habitat notes. For instance, “This one is from prairies and dunes,” or “This one is from moist, grassy areas.” Like you give us a hint. Are butterflies almost always where they are supposed to be like he said, or is it-

A. I would say more than birds, because a really large percentage of birds migrate, and so when they’re migrating you could almost find them anywhere. When they’re breeding then they’re more habitat dependent. Whereas butterflies, very few species of butterflies migrate. A few do, as almost everyone knows Monarchs do, and there’s a few others that do also.

But the great majority don’t really migrate, they just live where they are or they randomly move around. And almost always, you would find them in the habitat where they are. So if you’re looking for Hessel’s hairstreak [below], you’d spend your whole … If you just randomly were looking, you’d spend your whole life-

Q. [Laughter.] Marching around the universe looking.

A. … looking without ever seeing one because they’re only found in Atlantic white cedar bogs.

Q. O.K.

A. So, if you want to find Hessel’s hairstreak you basically have to go to an Atlantic white cedar bog. And that’s the fun thing about butterflies, is that, much more so than birds. They’re not only in much even more specific habitats, but their ranges tend to be much smaller, and so you have to basically …

If you wanted to see all the butterflies of North America, you’d have to go to almost every state. Whereas if you’re looking for birds you could see almost all the species in a year by visiting maybe five spots. Whereas butterflies, you have to spend many, many years going back to all the places because a butterfly may only fly in the Wind River Mountains in Wyoming and it only flies for one-week a year.

Q. Oh, my goodness.

A. Yes. Exactly.

Q. Are you sure this is what you wanted to do for how many years, Dr. Jeffrey Glassberg? [Laughter.]

A. That’s the fun part of that really, is that, you get to take these adventures. I had to go back there twice. I had to get a horse and go up to 12,000 feet and, while we were … A couple years ago, my friend and I were in Alaska for a couple of weeks flying on sea planes into remote lakes in Alaska where there are no roads.

So that’s the thing, it’s fun. But you don’t have to do that. Of course, you can enjoy all the butterflies in your own garden. And so that’s the beauty of it. You can just say, “Oh, I’m just going to see what comes into my own garden and have fun now.” Or you can say, “I’m going to travel around and see all the butterflies other places, too.”

Q. Yes. Another comparison to birding, which is what I know a little bit more about than butterfly watching: There’s that expression G-I-S-S, GIZZ or GISS, General Impression of Size and Shape. So, the first thing you want to do … So tell me about that, I’m out there, I see something fly by. I want to sort of, zero in on it. What are those sort of hallmark features that you want me to look for?

A. Let me say first, butterflying, it’s like anything else. The more you do it, the more you practice, the better you get at it. So whether it’s playing the piano, whether it’s playing basketball, whether it’s writing. Whatever it is you’re doing, the more you do it, the better you get at it.

Q. Practice makes perfect.

A. That really is completely true. So if you spend a lot of time looking at butterflies you eventually get to the point where you don’t even know what it is, you see it, and you know what it is right away. You don’t why, you can’t even put it into words necessarily. So you eventually get like that.

But before you get there, the place to start is, as you said, is with the idea that there are these six families of butterflies. And so it’s really pretty manageable. If somebody went out in the field with me for a day, I think it’s fair to say that after the … now let me say, some people are better at this than other people. Some people can’t do it at all and there’s other people that are great, and of course most people are in between.

But for an average person, if they went out with me in the field for a day, by the end of the day they could recognize a swallowtail. They’re large, they have a certain kind of flight pattern, most of them have tails, not all of them. Almost everybody could recognize a white or a yellow, so even, my 4-year- old grandson would say, “Oh, there’s a cabbage white.”

Q. Right. “There’s a cabbage white.” [Laughter.]

A. Exactly. And butterflies, of course, they’re really named in a very technically onerous way, like the white ones are called Whites and the yellow ones are called Yellows, so that makes it easy. And the same thing with the other families, with the gossamer-wings, which are the hairstreaks and the blues. Once you see them, they’re small and delicate and have a certain kind of flight, you pretty much start getting, “O.K., it’s in this group.”

So that’s the way you start. You start by recognizing, “It’s a swallowtail, it’s a blue. It’s in one of these six groups,” and then that helps you get to the right place in a book, and then you start. After you do it a little bit more, then you learn the subgroups. You learn, “O.K., it’s not only a gossamer-wing, but it’s a copper, or it’s a hairstreak, or it’s a blue.”

And now you’ve got that subdivision. And then as you get a little bit more experienced, you learn the subgroups within that. And so that’s how you start, and it’s a lot of fun. Basically, there’s people that do gardening for butterflies, so it’s very relaxing that way. You can look at it like an active video game. You go out, and you’re out in the wild in some places where there’s literally thousands of butterflies flying around you and flying at you and so forth, and you have to quickly identify all the ones. It’s kind of like a video game.

Q. [Laughter.] Yes, you mentioned flight pattern and I have to confess that every year when the summer’s approaching and monarchs and viceroys may be around and their similar coloration, though obviously, especially to someone like you quite different. One of the ways, I always go and I look up their flight pattern, which is different, it’s very different, even if I’m not close to them I can sort of infer which one it is.

A. Exactly. Exactly. Monarchs [above] kind of sail more, they fly in a V. And viceroys [below] fly in … they tend to be flat wings that they flap in a very shallow way. Exactly, once you get some experience … pretty much when I go to somewhere, even when there are thousands of butterflies, it usually takes me something like truly less than a second to be able to know each one, what it is.

Q. I want to say thank you for putting the index of food plants in the back of the book. Again, being a gardener, and also trying to learn to identify these relationships between the different species and the plants that they’re reliant upon and prefer, that was great.  So you don’t only have the species of butterflies, you have the actual separate food-plant index, plus that visual index I mentioned before. So, that’s a great thing, too.

But I want to talk about the North American Butterfly Association.

A. Sure.

Q. Tell me about that.

A. So the North American Butterfly Association is the largest group of people in North America that are focused on butterflies, and we’re focused on getting people involved with butterflies, educating people about the importance of butterflies—I’ll talk about that in a second—and working to conserve butterflies. So we do all of those things.

We conserve butterflies directly. If it wasn’t for the North American Butterfly Association, it’s almost certain that regal fritillaries would be gone from the Eastern United States, for example. And we’re involved in conserving butterflies.

We own and operate the National Butterfly Center down in Mission, Texas, and we have a very big educational center and also a conservation center down there. We monitor butterflies, we have the largest database of butterfly abundances in the world, we have chapters throughout the country. So we’re involved in all sorts of ways in trying ultimately to conserve butterflies.

Q. And is there an equivalent of like eBird or like a database where I can, as a citizen scientist, contribute my sightings. Do you have that?

A. Yes, we have a site called We Butterfly. And you can go in there and enter your sightings. And it all goes into a database that’s used by scientists.

Q. And so the website for the North American Butterfly Association is NABA.org. Is that correct?

A. That’s right. The main website is NABA.org and then the We Butterfly is WeButterfly.org.

Q. Just to wrap up: within this diversity of butterfly species in this book or … especially in the North America, do you have a particular passion? Because you don’t show any prejudice or show off anybody more than another, obviously, in this kind of a book. [Laughter.]

A. Yes, in all honesty, my favorite butterfly is the one I’m looking at the moment.

Q. O.K. That’s like me with plants. O.K., I get it.

A. [Laughter.] One other thing that differs from birds—plants may be like this in some ways, in a different kind of way—is that, each one is different. There’s more variation amongst its different individuals of the same species than there are among different bird individuals of the same species.

And in addition, the butterflies get worn, they age. So, as they get older, they’re like people, they get nicked up and are not thought to be as attractive by other people, and that happens to butterflies too. They get nicked up and more and more beaten up, so that after they’ve been flying for quite a while, they may be missing almost all their scales and big sections of their wings, and there’s almost nothing left.

But when they first emerge from the chrysalis, all of the butterflies are beautiful. They’re in pristine condition. There’s usually a residue, a little bit of an oily residue that creates a sheen in the sunshine that just creates all these beautiful effects. So when you see a really freshly eclosed butterfly, no matter what the species, a little brown skipper, it will be gorgeous. So you look for those. Each time you see a butterfly you kind of see it for the first time.

Q. Ah, the beauty of youth. [Laughter.] Oh well, I’m so appreciative of your time, Dr. Jeffrey Glassberg.

more from jeffrey glassberg

enter to win the butterfly i.d. guide

I’LL BUY A COPY of the latest edition of Dr. Jeffrey Glassberg’s “A Swift Guide to Butterflies of North America” for one lucky reader. All you have to do to enter is answer this question in the comments box at the very bottom of the page:

Are there butterflies that you count as regulars in your garden–any that you are confident in your I.D. of, or that you particularly enjoy seeing? (I’m always delighted at the miracle of the mourning cloaks’ flight in earliest spring, since they manage to overwinter here as adults, and also love seeing the pipevine swallowtail and spicebush swallowtails–since I grow both Aristolochia and Lindera, pipevine and spicebush, which their caterpillars depend on.)

No answer, or feeling shy? Just say something like “count me in” and I will, but a reply is even better. I’ll pick a random winner when entries close at midnight on Tuesday, May 15. US and Canada only; good luck to all.

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MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its ninth year in March 2018. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the May 7, 2018 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).

  1. Jane R says:

    We always see monarchs and swallowtails in our garden. Last summer I saw a question mark for the first time, and that prompted me to grow false nettle this spring. I never thought I’d tenderly nurture a “weed” from seed, but I guess you can teach an old dog new tricks

  2. Katrina says:

    I’ve been looking and wanting a guide to come out like this! I’d be able to learn and then be able to teach others more about butterflies

  3. Louise Oppedahl says:

    I see Monarchs and Swallowtails in my garden. I’d love to learn more about what plants the butterflies like. With Swallowtails a few years ago I kept planting dill and parsley, I think.

  4. Kristina Miller says:

    My husband got me started on butterflying and our garden is planned around attracting them with both food and nectar plants. Depending on the season, we regularly see monarchs, tiger swallowtails, spicebush swallowtails, black swallowtails, question marks & commas, sulphurs, buckeyes, red admirals, american & painted ladies, great spangled fritellaries, red-spotted purples, a variety of hairstreaks, little blues, a large variety of skippers including the silver spotted skippers, and, of course, cabbage whites. I have been lucky enough to have a few giant swallowtails and also one that laid eggs on my rue plant so I had a caterpillar as well which is unusual for NJ. We have more unusual visitors as well and it is always a thrill to see a mourning cloak, long-tailed skipper, snout, viceroy, or a pearl crescent AND OTHERS!

  5. Kathy O. says:

    This was fascinating. I’ve been seeing many more butterflies this year than I have in the past and it’s very exciting. Don’t know the difference and would love the book to help me.
    Thanks for everything, Margaret.

  6. Kaaren Hart says:

    I am in the PNW and I see Swallowtails and Monarchs. There are many more (besides ‘Cabbage Whites’), but I don’t know what they are at all. I also would like to onow the distinction between a moth and a butterfly. The book looks so yummy!!

  7. Paula says:

    Our garden club has created a butterfly meadow with native plants on our Town’s historic green opposite our library. We have many kinds of butterflies and other pollinators dining on native plants.

  8. Janet Vallar-Gillette says:

    I try to hatch several caterpillars each year. Have planted Dutchman’s pipevine, milkweed, heliotrope and several other favorites. Love watching them grow, pupate and hatch.

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