getting to know your garden insects, with dr. david shetlar

WHEN THE NEW SECOND EDITION of “Garden Insects of North America” arrived recently from Princeton University Press, I quickly went down a rabbit hole. Well, maybe it was down the burrow of a tiger beetle, or a ground nesting wasp. But at any rate, I got lost in the sheer amazement of this long-indispensable reference, and how it can help us in our gardens.

Dr. David Shetlar (below left) is a professor of urban landscape entomology at Ohio State. With Dr. Whitney Cranshaw of Colorado State (below right), author of the original 2004 edition of “Garden Insects,” he created the second volume, and joined me to explain who’s in the updated version and why, and how we can get to know them better.

Plus: Enter to win a copy of the new “Garden Insects of North America” by commenting in the box at the very bottom of the page.

garden insects, with dr. david shetlar


Q. What an undertaking this must have been. How long was this collaboration?

A. Well, it was kind of interesting, Whitney and I had met at one of our national entomology meetings, and he came over to me and says, “You know, Dave, I’ve been noticing you have all these pictures of these insects, and you keep chiming in to our blog. Would you be willing to help me revise the book?” And I was kind of taken aback by it, but I said, “Sure, let’s give it a try.”

Q. Yes. And how many years ago was that meeting?

A. That was really only about four years ago.

Q. Wow, impressive.

A. And it took us the first year just to get all the paperwork done with Princeton, and they said that yes, they were happy to have a revised version and so forth, so it really was about a two-year effort.

Q. I’m impressed. So, of the estimated 100,000 plus insects, and other arthropods in North America, you had to filter somehow to decide who would make it into this revised edition. How do you even do that? What’s the filter, of who’s deserving of being in here?

A. Well I think the title says it all. We really wanted this … we sort of waxed and waned to rename this as sort of the landscape insects, but then that might leave the gardener people out, and so forth. So we just stuck with the garden insects, but it’s really the critters that you might find not only in your fruit and vegetable gardens, but also in your flower gardens, and even in your lawns, and basically anything that might be going on in that urban habitat.

Q. I mean, we gardeners really want to oversimplify, and probably for most of it’s that we don’t have a science background, and we feel uncomfortable so we make categories like “good bugs,” and “bad bugs.” And I suppose, like if you’re a black locust tree, if you’re a Robinia, then like a locust borer is not a beloved friend. But I have trouble looking at a locust borer, which is beautiful insect, and familiar to me—I don’t see that as an enemy. So you know what I mean—like how do you decide who’s on the beneficial side and not on the beneficial side? [Above. locust borer on goldenrod, and its damage to a locust tree; photo by Whitney Cranshaw.]

A. [Laughter.] Yes, well, we get that all the time, and I’ve got some dear friends who just hate bugs.

Q. Yes, boy.

A. And to them, any bug is a bad bug, and I say, “Well, O.K., you can laminate it on the bottom of your foot, if you want to.” But the reality is, is that most of the insects that are in our landscapes and gardens are either beneficial, and hopefully we’ll get to talk about some of those beneficial attributes later one.

Q. Yes.

A. Or they’re just basically we throw up our hands and we say, “We don’t know what it’s doing here; it’s just innocuous.” And let it do its thing. It’s not going to hurt your plants, it’s not going to hurt you, and just let it go about its business.

Q. So, is it always the case that introduced insects become pest species? And I guess my introduced, I mean not only from another country, but even sometimes from another region, right?

A. Sure.

Q. They move around. So if it’s introduced to an area, is it a pest—is that always the case?

A. Not necessarily. We have a lot of introduced insects, and other organisms, that in some cases, we didn’t even know they were here for a long time until somebody said, “You know, I’ve never seen this before, what is it?”

And we send it up to the taxonomist, and they say, “Where did you get this?”

Q. [Laughter.]

A. And we go, “Well, in my backyard.” And they go, “Oh. Well it’s not supposed to be here.” And so again, what we find, is there’s probably dozens of introductions that may be even going on now that we’re unaware of. The important ones, of course, are the plant-feeding introductions. And in some cases, the disease-vector introductions. Everybody’s familiar with the Asian tiger mosquito.

And frankly, if it didn’t vector diseases that we were worried about, nobody would pay much attention to it. But it is an important vector, so we do have to manage it appropriately. And the same with the insects: If it’s an insect like the emerald ash borer, that’s going to kill all the ash trees in North America, we pay attention to that pretty quickly.

Q. Right. [Above, emerald ash borer photo by David Shetlar.]

A. But if it were, let’s say, a foliar-feeding aphid on the ash tree, we may not have even noticed it for a while. Because it’s not going to kill those trees, and would be more of a nuisance factor than anything else.

Q. The book’s arranged to be most helpful for real-person use. The chapters are according to what action that insect is taking, and where on the plant, isn’t it? So it’s really helpful.

A. Yes, I’m glad you noticed that, because that was one of the first things that Whitney and I had to sort of arm-wrestle over.

Q. Uh-oh. [Laughter.]

A. The original book was actually done, like most entomologists, we sort of grow up using taxonomy. And so we lump all the beetles together, we lump all the caterpillars together, we lump all the things that suck, meaning the true bugs, together.

And the reality is when you see it, you’re going to see something on a leaf. Or you’re going to see something on a stem of the plant, or if you dig it up you might find something in the soil. So, we went back and tried to rearrange the book, primarily by where you see this thing, and what kind of damage does it cause when it’s feeding in that area.

Q. So there’s the chapter on insects that suck fluids from leaves, there’s one on roots, those that feast on a root, or tuber or soil, or at the soil surface, and ones that can be found in large branches, and trunks of trees and shrubs, and etc. So it’s right away, I can narrow down, as a gardener, even as a layperson, compared to not knowing which order … you know what I mean, it’s in, in the whatever.

A. Right, or in the case of my entomology students, I want them tell me what family it’s in—not necessarily just the order. [Laughter.]

Q. Yes. So, I thought that made this book very, very … and I have the original book as well. But that made this very helpful. It was like right away I could get down to business. And I was selecting, I was narrowing down the possibilities, and going to avail myself of the learning quicker than spend all my time keying something out.

A. Right.

Q. So … and of course, then within those … once we get down to … it’s not that the taxonomic isn’t there, you do tell us groups of related creatures, and their life histories, and their habits, and information on their distribution, like in the previous version of the book.

A. Yes. And we have to do that. The reality is that most of the leaf beetles do the same kind of feeding, and so there’s probably 30 different kinds of leaf beetles that attack different plants here in North America, but most of their damage is pretty similar. The life cycles can be a little bit different, but once you learn one leaf beetle and what it looks like, you should be able to quickly identify the rest of the leaf beetles.

Q. Yes. It was funny that Chapter 2, insects that chew on leaves on needles, is so big, it’s bigger than any of the other chapters. It’s giant.[Above, Viburnum leaf beetles by David Shetlar.]

A. [Laughter.] Yes. Well, and there’s more plant foliage out there than any other resource. So that’s obviously going to be the biggest.

Q. Yes. And a completely new, besides this sort of new arrangement that you wrestled over, Chapter 8 is new, completely new, isn’t it?

A. Yes.

Q. And what’s that about? Tell us about that chapter.

A. Well, we really felt that people need to know not only the bad actors, but the good actors, and the ones that we think are beneficial, and again, Whitney and I kind of wrestled over this, because there are a couple of other books out there that deal primarily with the so called beneficial insects.

Q. Yes.

A. But we wanted to take that a little bit further. Typically when people talk about beneficial insects, they always say, “Well, the predators and the parasites,” or parasitoids, but it’s a bit more complicated than that. The other thing when we mention beneficial insects, most people say, “Oh, you mean pollinators.”

Q. Right, I think that’s what everybody thinks. Yes.

A. Yes, and that’s true, but pollinators are not just honey bees. There’s a whole suite of pollinators out there. I was just admiring last night, on one of the nature shows, this beautiful photography showing how butterflies were picking up pollen on their wings, and dropping it off at the next flower. It was just fantastic to show that. So there’s another reason for having butterflies and moths in your garden, it doesn’t just have to be honey bee.

Q. And another good reason: I’m crazy about moths, and another good thing that I tell people is and they make caterpillars, and we wouldn’t have many baby birds, or songbirds, if we didn’t have caterpillars, so-

A. Right.

Q. That’s a good thing, too.

A. Yes, that’s absolutely right there.

Q. It’s the baby bird food.

A. And actually, that’s one of the reasons why some people are saying we need to plant more native plants. Because a lot of people are unaware that if you plant … and I’m not picking on particular foreign plants, but if you have something like a sugar maple versus a Norway maple, there will be many more insects on that sugar maple that the birds will feed on than on the Norway Maple. So it’s a whole ecosystem going on out there.

Q. Yes, I think maybe at Audubon I read some stat not long ago about like Ginkgo supports five species of caterpillar, or moth—excuse me, of butterfly or moth—and native oaks support 500 or something.

A. Right.

Q. And it’s that drastic. Tell us some examples: Who are these kind of good guys besides the pollinators? So there’s like all these beetles, and flies, and…

A. Well, when we get to the predators and parasites, it always amazes me. I have a joke with Master Gardeners, I show them a picture of a wolf spider. And I say, “Can you imagine that your lawn-care person comes up to the door, and knocks on the door and says, “Mrs. Jones, I’ve brought a biological control that’ll be useful in your yard.” And you open this box and here’s this big wolf spider, you can imagine that Mrs. Jones is not going to be pleased about that.

But that’s the reality. A lot of these things like ground beetles, and even crickets—the black field cricket is primarily a predator, and is feeding on things. One of my fellow entomologists, we were having a meeting in our turf entomology, and he says, “Ants rule!”

And what we were talking about was that we had just finished a discussion about how many caterpillar eggs, like sod webworms, that these ants were eating, and how many grub eggs the ants were eating out there. And so, ridding your landscape of all the ants would not be a good thing. They are very beneficial in many ways. [Above, wolf spider photo by David Shetlar.]

Q. So they provide … and in the book you call them, they provide services, don’t they, these beneficial insects?

A. Yes, the entomologists, we’re like everybody, we try to develop euphemisms that won’t be upsetting or alarming to things, and one of them is “services.”

And I really kind of like the idea, because in this case, I quite often, when I’m teaching the general entomology course here, and we get to the flies, and a lot of people are going, “Eew, maggots and flies,” and so forth. I say, “You know, if it wasn’t without those maggots, we’d probably be up to our armpits in animal poop and dead bodies.”

Q. Yes.

A. And they get kind of wide-eyed and look at you, and go, “What do you mean?” And I said, “Well, these are the primary recyclers of dead material.” And so, that fly that lands on that poop that your dog left behind is there to lay eggs on it so its larvae, or maggots, can devour that and decompose it, and break it into smaller components that the soil can use.

Q. Right, so these are services, right.

A. And same thing, I challenge people, if you drive down the roadside and you see a poor skunk or raccoon or something that’s been biffed at the side of the road, make a mental note of that. And I guarantee if it’s in the summertime, in about 10 to 14 days, that skunk or raccoon will be gone. And most people think that, well, something drug it off, and no, it was fly maggots that came in and ate it all.

Q. Yes. It’s interesting, I go out at night looking for moths, and if you go out at night, even in a familiar place like your own backyard, or just your own front walk, you see all these creatures who are busy working, and a lot of them are … I think they’re detritivores, some of them are detritivores, they’re going about the business of kind of housecleaning, and recycling, right? I mean, there’s all kinds of creatures out there doing work at that time.

A. Yes, and it’s one of the reasons why we tell people to leave the clippings on their lawn. Because most people are just thinking, “Oh, it’s fungi and bacteria.” No, there’s a whole squadron of small insects and other arthropods that chew it up, partially digest it, and break it down, and then the bacteria and the fungi break it even further down to basically make the humic acids and things that we need in our soils to have good soils.

So by removing those, you’re doing two things. Number 1, you’re removing the food that all those organisms recycle. And Number 2, you’re removing some nutrients from that. So just leave the clippings there, and they’ll help fertilize your turf and grow all these organisms that make for healthy soils.

Q. The beetles: that’s a big group, the Coleoptera.

A. Coleopterists are always proud to point out there are more species of beetles on this earth than all the other species combined. And right now, they’re at about 500,000 described species-

Q. Wow.

A. And most of the Coleopterists that I talk to say, “If we could get to the tropical rain forest before they’re all cut down, we think we’d be well over a million species of beetles alone.”

And so again, I kind of have to chuckle at my bird watching friends. They love to brag about their life list of … “I’ve got 1,500 birds on my life list.” And I kind of chuckle and say, “There’s that many species of beetles in your backyard.”

Q. Yes. And I read about certain kinds of ground beetles, and rove beetles, some soldier beetles, certain blister beetles that feed on grasshopper eggs-

A. Mm-hmm.

Q. Do a good service, so to speak, and I’m wondering like how do I make my place more attractive? What is a happy world for beetles? [Laughter.] What do they like? Like I want more of them. When I read that Chapter 8, I want more of them. I mean, I think I probably have a lot of them, but at any rate, Yes. [Above, rove beetle photo by Whitney Cranshaw.]

A. I guess my feeling is, and again, the people that I actually work, I with the lawn-care industry, and the tree- and shrub-care industry, and so forth. But I harp at them continuously: I have no problem with you using a pesticide in your yard, but only use it where it’s needed and when it’s needed.

Q. Right.

A. And don’t come into a property every month or every other month and hose everything down. Because all you’re going to do is kill all these beneficials, all these service providers, in the landscape. And one of the problems that we have with them, is they’re not as good at building up large populations as the insects and mites that are pests. The pests are great at reproduction. And some of these others aren’t very good. So if we conserve them, and that’s my normal statement—let’s just conserve what we’ve got, and we will do better in the long run.

Now, I find it interesting when you talk about providing habitat, again, a lot of the habitat is something that those of that are gardeners generally provide. And what I’m talking about is the “sloppy gardener.”

Q. Right, a little bit of leaf litter, and a little messiness here and there, right?

A. Yes. Leave a few rocks in the garden—that’s O.K. And if a branch falls off of the tree, you can leave it there, you don’t have to pick it up and throw it in the yard waste. Just leave it there, that will provide places for these critters to hide. And food for them, and so forth. And so, you don’t have to have this immaculate, manicured landscape to have a pretty landscape.

Q. In the book introduction, you and Dr. Cranshaw both mention in your collective voice, that one reason for an update after 14 years was a change in the capabilities of insect photography. And I also noticed that many of the images bear your personal photo credit. Is there anything you want to suggest to those of us who are out there with our cameras wondering how we could do better at it? I guess my special disability is that I do it at night, because it’s moths and stuff, and that makes it just even more complicated.

A. Sure. I think the rise of the digital camera has had a pronounced effect on anybody taking nature pictures. Because in the past, I started out using a macro lens on a 35mm camera. And I first started out with a 50mm macro lens, and I finally realized that I need to go to a 100mm macro lens to give me what they call working distance.

But I am just absolutely shocked now. My wife used to harp at me, “How much money are you spending every month on all this film?” [Laughter.]

Q. Right, film.

A. And now I can click away like mad, she doesn’t say a thing, and when I get back to my computer and download all the pictures, I go, “Nope, that didn’t work, nope, that didn’t work, yes, this is a keeper.” And so it’s just changed the economics of it.

But on the other hand, I just … it’s jaw-dropping the pictures that people send me. I get former students sending me pictures, I get Ohio citizens that are sending me pictures all the time, and I’m going, “Wow! How did you do that?” And they say, “Oh, I did it with my cellphone.”

Q. I know, it’s amazing, right. I can barely take a picture with my cell phone, I’m terrible at that.

A. Well, and that is something that I would point out. When I used to use 35 millimeter, and I prided myself on my insect images, and I had at least three other entomologists that said, “Dave, would you tell me every bit piece of your equipment?” And they would get it, and then they would either call me up or send me an email, say, “Hey. I’m still not getting good pictures.”

And I guess the bottom line, you do have to have kind of a composition eye.

You’ve got to have that eye for, “O.K., I’ve got this critter kind of in the frame, there’s no distracting stuff in the background, and now I’m going to take the picture.” And you have to have kind of a little bit of an artist eye, I think, to do that.

Q. Well the book is loaded with them, including many by you. Dave Shetlar, I’m so happy that you made time to day to speak with us the second edition of Garden Insects of North America, and thank you for the heroic job that you and Dr. Cranshaw did to make this book possible.

enter to win ‘garden insects’

I’LL BUY A COPY of the new “Garden Insects of North America” by Whitney Cranshaw and Davis Shetlar 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:

Is there a type of insect you’d like to have fewer of–someone who’s your worst “pest”–and is there someone you wish you had more of in the garden?

No answer, or feeling shy? Just say something like “count me in” and I will, but an answer is even better. I’ll pick a random winner after entries close at midnight on Tuesday, April 24. Good luck to all; U.S. and Canada only.

(Photo top of page: Mexican bean beetle larvae, photo by Whitney Cranshaw.. All photos from “Garden Insects of North America.” Used with permission.)



  1. Leelaine Picker says:

    I’m determined to convince my granddaughters (and son in law) that most insects are beneficial. Put down the spray. Don’t shoot.

  2. Jill Beringer says:

    I would love to be able to identify bugs- good or bad- if they wouldn’t move so fast! Also, to identify them by the damage they do :(. I am panicked by all the invasive insects wrecking havoc where they don’t belong. Would love a copy of your book!

  3. Kathy T says:

    I am fairly new to gardening and trying to identify helpful vs. harmful insects. Definitely don’t get along well with the squash bugs but love the lady bugs and praying mantis.

  4. Julie Morgan says:

    We had a Good Bug Bad Bug category in our Photography Exhibit at our Master Gardener Spring Fling and the purpose is to involve the public but especially the children and the results were fabulous. All total we had 225 photos (8×10’s), some absolutely intriguing but a young man, maybe four years old was looking at all the photos and the one that drew him in was the Potato Bug instar- he carefully put the number of that photo on his vote and looked extremely pleased with his selection. An updated book would get a workout in the MGExtension Office. Thank you for updating the world of insects for those of us that delve into that buggy world.

  5. Lauren Waite says:

    I’d like to limit squash vine borers in my garden to just a few so I could grow zucchini and cucumbers and get a few from each vine.

    More? Hard to pick one — monarchs, if I’m forced to choose.

  6. Christine says:

    I am currently reading Lisa Zeiglar’s book, Vegetables Love Flowers, and I am introducing flowers into my newly expanded vegetable garden this season. I would love to learn as much as I can about the predators I will hopefully be attracting and the pests they will be helping me keep under control in my garden the natural way.

  7. Kathy Lehmkuhler says:

    We use no pesticides in the garden and have large areas of leaf & small branch litter. Since beginning this practice we have been amazed by the variety of insects in our gardens and the bird population has greatly increased too. I’d like less mosquitoes….

  8. Amy Collier says:

    The one insect I wish would leave my garden forever is japanese beetles. I wish I had more beneficial insects like ladybugs or green lacewings.

  9. Anne says:

    I like ladybugs and the different native bees that I see in my garden. I’d love to see more types of butterflies.

  10. Joan says:

    Bees, I love to see bees in my garden!!! Once I found a nest of bumblebees under a fairy statue in my garden! Unfortunately, they departed the next day after I accidentally disturbed their nest!
    They’re such beautiful, productive creatures. The collapse of so many hives in recent years is a real concern.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.