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Holly Walker is a Plant Health Specialist at Smithsonian Gardens. I sat down to talk with her on November 27, 2017 about entomology, her background and some of her current undertakings with Smithsonian Gardens.

Could you tell me about your role with Smithsonian Gardens?

My title is Plant Health Specialist, but it’s a wide umbrella of different things. My primary goal is to take care of the various plants, and it’s different from the horticulturalists and the gardeners in that my job is to look at insects, look at plant diseases and pathogens—anything that might affect the plants, things that might have negative impacts on them—and to create management plans with the gardeners, with the horticulturalists, and talk about options. A lot of what I do is about sustainability. We do use some chemical insecticides and pesticides, but when we do we want to make sure that we’re being as safe as we can, that we’re using the least toxic things.

My background is very much in integrated pest management, which is an idea that you try and start with other things first before going to really heavy stuff that might have an impact on the environment. We’ll do cultural controls before anything else, or mechanical controls if we can. There’s a wide variety of different tools that you can use before you have to break down to using any kind of strong pesticides. But if we do we make sure that we’re doing everything regulated in a way that it’s safe for the environment, it’s safe for people, it’s safe for animals.

Another side of what I do is I’m very concerned about pollinator health and animal health, so making sure that we’re having the least amount of impact on those groups as possible. We want to promote good insects, organisms, and wildlife in the area. So a lot of time I’ll use things like biological controls, which is the use of beneficials or nematodes or things like that to try to control pest issues that we have. A big thing for me this year has been getting our biological control program up and running so that we don’t have to use chemical insecticides or we can really reduce that in the environment.


How did you come to work at Smithsonian Gardens?

I have experience with this at a different place. I was at Longwood Gardens doing integrated pest management. I did that as an internship. But before here I just finished my Ph.D. in entomology at the University of Delaware. That’s where I was just prior to here. I found the job online. It was really interesting to me because it had such a broad spectrum. Of course working at the Smithsonian, it’s just one of those places that, ever since I was a kid, I hate to say it, but you fantasize about working at a place like that. It was such a cool opportunity. I really wanted to jump at this. It was a really good chance to have a big impact.


Did you have some key experiences as a child, with nature, with insects, with gardens, that, when you look back on them, may have led you to this career?

I always wanted to do something with biology. I liked living things and natural things. For the longest time I actually wanted to be a marine biologist because I grew up on the waters and the bays around here. I grew up in Delaware. Entomology came to me much later on.

It’s funny because I didn’t want to do entomology at first. I had picked up a job working for a USDA lab doing research on beneficial insects. I was also working another job during the summers working on mosquito control and how they vector different viruses. One of the people I worked for was an entomologist at the University of Delaware. I was there as an undergrad. I was in the biology department. One of the entomology professors from the other department kept trying to push me to take entomology classes and reconsider being an entomologist. I remember telling him very specifically, “No, no. I’m not sure that this is something I want to do. You have plenty of students who know this is what they want to do. I just want to do biology.” Then I graduated and I was looking for jobs and trying to figure out what I was going to do next and that’s when the internship at Longwood Gardens came up. I originally applied for a research position there, but the integrated pest management group contacted me and they said, “I know you applied for research, but we think you have a really good skill set for this. Would you be willing to give it a try?” I did at that time have some experience working with insects and so I said “Yes, I would really like to do this.” And it was very much that year of in-depth integrated pest management, learning about biological control, learning about all these different factors, and putting a lot of my own knowledge of ecosystems and biology to work, that got me interested. It was after that I realized I wanted to be an entomologist. I wanted to continue working in this field.

Do you have a specialty?

I’ve worked in a wide variety of different positions in entomology, everything from agricultural research—I used to work on West Nile Virus studies—to pollinator research. But what it really comes down to is that I mostly work with plant-insect interactions. I specialize in that area. I have a little bit more broad knowledge in other things. I’m always trying to improve in other aspects, because I want to get better at diseases, pathogens and those types of things. There’s some aspects that I’m still learning, but I think having that broad biology and ecology background really helps me to put it all together and figure out how everything’s impacting each other. That to me is the bigger picture. You need to know the rules behind it, be able to see all the pieces that you’re affecting, and how changing one thing or doing one thing can really impact the ecosystem, especially when we’re talking about the urban habitats.


With this ecological approach, you must work with a wide variety of other professionals in doing your job. Who are some of the other people that you work with on a regular basis?

Weekly I work with almost all of the lead horticulturalists and the various gardeners. So every day I go out, especially during our scouting seasons, I go out and I’ll meet with the lead horticulturalists for each museum. I’ll go and I’ll do a full scout of the area and then I’ll come back with any information that I’ve found—any insects, any diseases—and then we sit down and we have a discussion about the health of the plants, about what the long term of that plant is, what we want to do, what are some of the risk factors, what things do we need to consider, like are bees pollinating right now? Is that something we need to be concerned about? What other plants are around them that might be sensitive to anything we were to try? So we develop this plan to try and manage whatever the problem is. And a lot of times it’s not an instant fix, it’s something that’s long-term or may be something we need to keep an eye on.

I work a lot with the University of Maryland because I send a lot of samples to them, particularly for plant pathogens. Here I work with our arborist Jake, and he’s really great. We’re working with some of the trees in the Kogod Courtyard that have been having issues. There’s a lot of stress on them. Together we’re working on this management plan to watch the trees, see what’s working, and suss out what some of these different stress factors are, so we can start relieving that as much as possible. So it just depends on what the job is.

The other side of it is I work a lot with Education because I do a lot of outreach as well. I got involved with Pollinator Week. This year I did the Garbage to Gardens program about trees and the importance of how trees recycle pollutants in the air and the impact of that. I did my own “Let’s Talk Gardens” talk this year, talking about beneficials and different types of insects you might find in your garden and how to be able to identify them at different stages.

This is my first year, so I’m just getting started with it, but in the long term I want to be able to do more where I’m teaching informal garden, insect and pest courses. I want to start with the gardeners themselves because I recently participated in the Sentinel Plant Network where you are looking for new and incoming pests that are going to arrive and they always talk about the fact that as horticulturalists, particularly in gardens, we’re the first people to see things coming in, and that by educating ourselves we can really help out and be the stewards of protecting our plants.


Did you have any role models or mentors or teachers that influenced the course of your career at different times?

I’ve been very lucky to have really wonderful people in my life. Most of them were later on in life because I didn’t really find my footing, and what I wanted to do, until later on. I had great professors. Lynn Mahaffy is a wonderful ecologist at the University of Delaware and she just has this passion for it that I just enjoy. I was really happy when I went back to grad school. I went back to University of Delaware and was able to actually help T.A. some of her classes and her field work. And I just loved it because I understand how wonderful it is to inspire people to get into this field and really have that curiosity about things and to follow through with their questions.

When I was at Longwood Gardens I was very lucky. I had a really great team—a guy by the name of Mike Leventry and of course my other was Casey Sclar. They were really the ones who taught me everything, at least the beginning of my passion for insects and entomology, particularly in terms of horticulture and integrated pest management.

There have been a lot of really wonderful people. I’ve had a lot of great people to support me, especially in entomology. It’s a strange field for a lot of people. People are always a little surprised when I tell them I’m an entomologist. But I’ve had some great teachers along the way. I know I’m probably forgetting quite a few, but that has been one of the most positive things and it very much encourages me that I need to do the same for others. I started out as an intern and somebody gave me an opportunity, and so I think it’s very important to do the same and to mentor other people.

I feel like my life has come in stages, and I’ve gone through all these different things, but there have always been people to be a support through those moments, who kept me encouraged.


What are some misconceptions about entomology? If you were to advise a young person who might be interested in some of the things you’re interested in, like biology, why consider entomology?

Entomology is really great. I know it’s often overlooked because most people have two gut reactions to insects. The moment you show them insects, there’s usually that “ooh!” or there’s that “ew!” and more often you get the “ew!” And I get it all the time. I deal with a lot of people who have fears about insects. I didn’t start out with those fears, but I wouldn’t say that I had quite the love and the passion that I developed over time. I just liked nature and I liked all things. As time has gone on I’ve become more fascinated with insects.

The other side of it is I’m still an ecologist and I still love the big picture. I see how important insects are. I’ve worked in a lot of different aspects of entomology. I used to teach a class on forensic entomology and how we use insects to actually determine time of death and all these other cases. I worked in agricultural entomology. We’re talking about food sources for all the world’s population, and with more farms being built, what are we doing? How are we trying to be sustainable with that? I worked with pollinators, which of course is a big issue, particularly native pollinators, especially in cranberry bogs. Then there’s the medical entomology side, which is the viruses and how do the affect us and our livestock.

I guess what I would say about entomology is it’s a huge field and it has a lot of practical applications that affect people all the time. People don’t usually consider it, but it’s actually a fantastic field of research. For me it’s always felt like a field where I’m actually doing good for people. I actually feel that the things that I do directly impact people or the way they feel, particularly with the gardens. By protecting the plants and doing it in a sustainable way, people can come into our gardens and they can feel good about the environment that they’re in. They can see not just the beauty of the plants, but the other things that rely on those plants and need those plants as part of their ecosystem. By creating these environments I’m teaching them something about this world that maybe they don’t think about. Insects are often overlooked, but they’re really important. They can be beautiful things in their own diversity.


There is a lot of talk about urban wildlife habit now. What does that mean to you and how is that going to affect your work?

I just came from the University of Delaware. There is a group there that I am involved with even more now called FRAME (FRAME: Forest Fragments in Managed Ecosystems). It’s researching the urban forest fragment idea. It’s talking about how important these urban landscapes are. I think there are different sides of it. One is this idea of education. We really need to teach people that even in a very small place you can create habitat for other things. As our world is expanding, human beings are creating less space for these other creatures. We need to make room for them because they’re very important. You might not appreciate that squirrel, but he has a purpose. We understand that bees are important, but there’s more than bees. The beetles, all the little things, even the flies, they all have a purpose. We need to educate people to appreciate those spaces and to create those spaces where they can.

The other thing is we’re so lucky here because we have this great environment, this great platform in which to do it. We really should be those kinds of role models. We really should be showing people what they can do, from the littlest bit to what’s optimal. You can plant all native plants if you want to, and that’s a great way to go, but even if you can’t or even if that’s not what you want to do, by adding a little bit here and there, by creating certain types of structures, even just changing the way that you do something, can create habitat for something and create a little bit more room for all the other little guys and do a lot for us.


You described some of the ways gardeners could aide beneficial insects, what are some of the other things that they might be able to do?

The primary things I think about, for most home gardeners, are to try to plant more natives if you can or provide food sources for other organisms. It doesn’t necessarily have to be for insects. It could be for birds. Sometimes leaving leaf litter is a good idea because there are a lot of decomposers that live it that and they use that to help energize the environment around them. Not always pruning your plants all the way back to the ground in winter time because they can provide food or shelter. A lot of people like to make little insect houses, but any type of shelter you can create is good. A lot of times when we turn up the soil or keep changing these habitats, we are allowing potentially invasive species to be introduced into these environments, but we’re also creating dynamic change that can expose a lot of creatures to harsh conditions and interrupt their life cycles. The more we can leave that, the better off we will be.

I understand that for different people that means different things. We do use chemical insecticides here, but we’re very cautious about what we use. I would encourage people to think about what they’re putting out there. You should check what you’re putting out—not all of them are safe. The organic movement is going in a great way, but not everything that is organic is necessarily safe. There’s still that responsibility. It’s really on the gardener to educate themselves before they put anything out there and look for alternatives.


You’ve spoken before about the difficult relationship between people and insects going back through history. What are some of the things you’ve learned during your career that might help people see them in a new light?

I do always think about the roles that they play. My primary example is cockroaches. Everybody loathes cockroaches, but only a very small fraction of all the cockroaches out there are really considered pests. Most cockroaches play such an important role in decomposing forests. They’re really good at breaking down wood and minerals and they’re such an important factor in those ecosystems that to lose them would be terrible. We just don’t appreciate the job that they do. Many people have the idea that once they meet a bad bug all bugs are bad. I still have people in my family who don’t like bees because they’ve been stung once.

We play into the fears of insects. We can’t relate to them. They’re very alien to us. That disconnect often makes it very easy for us to just want to eradicate them. The other side of that is the scurrying. Most people tell me they really hate the scurrying.

Another house pest that people really hate, and it’s not an insect, is the house centipede. They creep people out because they have little feathery legs, but they’re fantastic. They eat roaches, ants and anything that you would consider to be an indoor house pest. Most of the time they only come out at night so people usually don’t see them. It’s good that they’re there but people don’t want to know they’re there.

I think people don’t want to know that the insects are there, but they want to know that they’re doing their jobs. We want to know that the bees are pollinating. We want to know that the spiders are taking care of the flies. We want to know that the cockroaches are decomposing things. We want them to be doing the jobs. But when it comes to actually seeing, or interacting with them, we don’t like them in our spaces.

They really are beautiful things. They’re so well adapted in this world. They’re just phenomenal. The things that they can do, particularly the diversity in where they live and the things that they accomplish, for being such a small scale, is impressive. The fact that you have colonies and hives that work together in ways that we, as humans, can barely comprehend sometimes, but even when we do we’re impressed because we think that we’re the only ones that work that way. There are the ants that make the giant chains or floating rafts. Here is a very small organism that is working thousands upon thousands to do something much greater than themselves. I’m always very impressed with social insects and even eusocial insects. There’s this idea of group care and how they do care for each other, maybe not in the way that we think about it, but everybody’s involved with raising and cleaning and doing different tasks. There’s this understanding. Insects don’t have to communicate it the way that we have to communicate. They use chemicals and queues and interact with plants in such a different way than we can. I don’t think we realize how impressive they really are.


We still don’t even grasp the full array of all the insects that are out there and the things they are doing.

There’s more of them than there are of us. Sometimes we don’t appreciate them because we really can’t grasp their full potential. The people who really study them, who specialize in a particular group or subset, really dedicate their lives to it. It’s a lifetime to really understand a small group. Yet we still don’t know all that’s out there, all that they can do. We’re learning new things all the time. That’s such a fascinating place to be.


It must make it a very exciting field to be a part of.

It does. Even when I worked in other fields, with invasive species, watching a new one get into an environment and seeing how they utilize new spaces, how they can change to that new environment and adapt, is impressive. We have to get ahead of them because we don’t want them doing damage, but it is really impressive to watch how well they adapt, how quickly they adapt to new things that other organisms wouldn’t be able to handle.


Do you have any favorite insects or insect behaviors?

It’s always very hard for me. Everybody always asks me what’s my favorite insect, but you have to tell me what order, what family, because I love a wide variety of them. I’ve had different moments with different types of insects that have spurred me to love different things. It’s funny as someone who enjoys pollinators, I do appreciate butterflies, but I tend to like them less than I like some of our large moths, particularly large silk moths, cecropia moths, luna moths, or even our imperial moths. I love raising them. It was a hobby I did through grad school. It was this joy of watching them go through their lifecycles. Someone brought me an Eastern Hercules beetle, which is the largest beetle in our area, and I kept him as a pet for a while. I fed him oranges. I was always impressed with his strength. He could pop the seal off a Tupperware container. He was that strong. He was just absolutely fascinating to watch.

I feel like no matter what field you get into you can love something about the insects that you’re working with. I worked with mosquitos, and I thought I could never love mosquitos. There’s a particular type of mosquito whose species name is sapphirina, and I didn’t understand until I put one under a microscope and on its back it has these unbelievable brilliant, iridescent, sapphire scales down its back. To look at it and to think about something that is so obnoxious to us, then to see something so beautiful about it, it blew me away. I’ve always been a little bit of that scientist at heart. Looking at insects under a microscope or seeing them up close, and really seeing them, is so phenomenal. I see them as these very beautiful things. And it made me stop and start appreciating the small things, not just in insect but in other things. We have so many things in this world that are tiny, but their structures are so perfect and so delicate, yet this fantastic functioning piece. I wonder “what did you have to do to get to this point?” That’s the amazing thing about them. Every time I learn about new insects and the things that they do, I think “That’s amazing that you’ve gotten to this point.” Particularly with plants and insects that they evolved together until they’re pretty much interlocked with each other because they need each other to survive. I love that.

I think this has been one of the most interesting things that I have ever done. This isn’t where I imagined myself years ago, but I really love this kind of work. I feel challenged in ways because there are always new things, new environments, and new situations. We’re always trying to better ourselves. Each day provides something different. At the heart of it, especially as a biologist, it is this chance to really look at the world, and look at the environment and watch it. I spend a lot of time observing and really trying to understand everything. Seeing that big picture, even aspects I don’t regularly see. If I do something here, what does that mean for our bays, our ecosystems further down? How do they impact each other? It really puts into perspective the role that I play and that it’s important to care about those things and to be an example of that for others so they know that they can do it too.

Interviewed by Nicole R., Smithsonian Gardens volunteer, November 27, 2017.