Insects in the Garden with David Lowenstein

March 16, 2021

Frequently Asked Questions

1. How do I know if an insect is beneficial or not?

Just like weeds, there’s no essential good/bad binary! All insects have their purpose, it’s mostly about what you want to cultivate in your space. For this reason, there’s not an easy guide for pests to encourage or discourage in your garden. We recommend getting up close and personal to check out buggy behavior, and then drawing some conclusions from there about what species you want to support or not.

However, University of Minnesota Extension does have this helpful guide identifying insects:

2. How do I attract beneficial insects to the garden?

In our conversation we talked about the importance of diversity in your garden – making sure you have plants at different life stages throughout the year (flowering at different times, various levels of vegetation, etc) is the best way to ensure many types of critters have food throughout the season. Diversifying your production can also help reduce any unwanted insects by practicing plant rotations and making sure there isn’t just one type of anything for them to feed on.

Consider using this handy dandy Plant Selection guide to help you find attractive plants for your garden! They have easily categorized plants into highly attractive, moderately attractive, and least attractive, so you can find a variety of plants that work for you.

3. It’s 65 degrees and sunny…Are you SURE I shouldn’t  clean up my garden yet???

Like many gardening decisions, some of it is choosing what you want to prioritize – If you’re trying to plant things soon or if it’s just a nice day and you want to get ahead of the game, it may make sense to clean up early. Our general advice is wait as long as you can, and you might be interested in checking out this recent article that answers this very question! Spoiler alert: there’s not a definitive answer! I know, we’re so helpfulJ

But check out this article from Oregon State Extension aptly titled “Should I wait to clean my garden in order to help conserve insects?” to learn more:



Video Transcript

{Abby} Okay folks, so we're gonna get started today. Welcome to Cabin Fever Conversations. As a reminder, if you have any points in time where you have technical difficulties, there's information on the screen about how to connect with the MSU Extension support team for dealing with that. And you can always watch us on the Gardening in Michigan Facebook page. I'm going to go ahead and stop sharing my screen and invite our other speakers. [Isabel] Hey everybody. So today we are talking with David Lowenstein, who is a consumer horticulture educator based out of Macomb County. David's an entomologist by training. And today we are going to be talking about insects in the garden. David, we're really happy to have you here. And we want to start off by asking, what about insects brings you joy? [David] Yeah, so thank you for having me on Cabin Fever Conversations. I'm an outdoors person. I like hiking, I like biking. And insects tend to be outdoors type organisms and things too, we find insects indoors and usually don't like that. So many entomologists sometimes have an idea that they want to be an entomologist, maybe something from their youth. They played with bugs, they learn something about them... for me, it wasn't like that. It was just kind of by chance that I had an opportunity to work with insects. And I learned a lot about the things they do and how they're involved in almost every facet of our lives. Food, Public Health. And I find them a cool system to work with because they're almost everywhere. They come in a lot of different sizes, shapes, colors. And they're just cool to observe when you find one that you haven't seen before. [Isabel} Yeah, I totally agree. Getting a closer look is always, the first step for me. It's like "WHAT is that creature?"! [Abby] So, you know, a lot of folks in our audience have some experience interacting with insects and their gardens. Do you have any thoughts on kind of what approaches people should take to insects and their garden or how should folks approach observing insects and their garden? [David] There are millions of insect species the world. And that doesn't include the ones that haven't been identified yet. So there are a lot of possible insects that you might find. One thing to consider is rather than kill first, ask later. Take a look at what is in the garden and maybe take a picture, observe what the insect is doing. Is it staying on the leaves? Is it on the ground? Are there certain times of day when you notice them more? So when you're looking at insects, you don't need to be a great photographer if you're trying to capture them. Although for ones that are mobile, like butterflies and bees. You probably want to have some speed or stay away because as you approach them, they will fly away. I'm not an insect photographer, so I can't unfortunately give any tips about that today. There are some entomologists that are really good at that. One in particular that comes to mind is Alex Wild. He's a curator at the Entomology Museum at the University of Texas. So take a look at it if you think you find an insect that might be new or you're not sure what it is, there are a lot of places online that you can search for insects or try to find what the insect might be to learn what it is in your garden. And that's the first step, figuring out "who is it?" and learning a bit more about what that insect might be doing. [Abby] I was laughing when you said don't kill first and ask questions later because I think so often we're surprised and our instinct is like "remove it from this space". And I've done that in the past and ended up finding out later that they were incredibly helpful friends. that would have been lifelong friends with my garden and, you know, and really worked in support of my garden dreams. And so just pausing long enough to slow down and observe and see what it's doing there. You can usually tell if that's something that's eating your plant or something that's just hanging out and finding some shelter and home there, you know. [David] I have one exception to that rule. Roaches, if you find roaches do not feel guilty about getting rid of them. That is the one insect I do not like. [Abby] Yah, I don't know if I would stick around and observe them. [Isabel] David, why don't you like them? [David] So I grew up in an apartment in New York City. And roaches are something that affect people from all socioeconomic backgrounds they're in the fanciest building on Park Avenue, they're in the tenements in the South Bronx. And they're big, they're scary, they're annoying. And I would actually pay my brothers to hit them with the shoe So I wouldn't have to be the oneto kill them. I do not like them. [Isabel] I grew up in Florida and we had palmetto bugs which are like the flying cockroaches. And I can still feel my stomach sink when I think about a flying cockroach! [David] Oh, sorry to have grossed anyone out today. I think that much of the rest of the conversation will be a lot more positive. Cool. [Abby]I get it out of the way. [Isabel] Yeah. Because we actually want to ask about, I think the term we hear a lot is "beneficial insects". So I was wondering if you could speak to that. Who are kind of the good guys in the garden. And why? [David] So a beneficial insect means that it does something that is positive. So we think of insects that eat our plants. Maybe they feed on clothes or they feed on food in our pantry. But the majority of insects are neither beneficial nor bad. They're just hanging out...looking for a place to stay, some shelter and looking for something to eat. Though those are okay to have the ones that are really good to have the beneficial ones. So insects that might feed on other insects. So things that feed on aphids or feed on other herbivores. There are also pollinators. I believe there was a previous episode where you learned about those. So anything that helps pollinate plants. So beneficial insects can come in a variety of different types. And I want to just share a couple with two slides about beneficial insects because this will help you determine what the insect might be. So I'm going to share my screen. And if you could confirm that it's visible with just a yes, that would be great. [Abby] not yet. [David] Okay. Let me try one more thing. I think it should work. Absolutely see it. Yes, excellent. So this is probably the most academic thing I'll show today. So there are two main ways that insects mature through their life. And this is a good way to figure out what the insect might be, which type of beneficial insects. So there are insects that go through what's called gradual or simple metamorphosis. And this is where the hashes an egg and they hatch from an egg rather. And they turn into a little insect larva. And they get bigger and bigger and bigger until they reach their adult life stage. So as an adult they have wings, they can fly, they can reproduce. So these tend to be soft bodied insects that would be in this category. And then there are things that go through complete metamorphosis. So they hatch from an egg into a larva, and that larva looks nothing at all like the adults, then it'll turn into a pupa or cocoon if it's a butterfly, and then something completely different. So the insects in this type of group, are typically beetles, bees, wasps are also within there. A lot of the bad guys are often simple metamorphosis, things like aphids, thrips, and soft bodied insects. So there's beneficials in two categories. There's the predators, things like lady beetles, beetles that we're most familiar with. But there's another group that's really unique and probably the most abundant of all beneficial insects. And these are called parasitoids. So parasitoid is something that lives part of its life, either within or just outside of another insect. So these are two examples. This is a wasp that lays its eggs inside the larva of some caterpillar. The caterpillar continues to feed for a little bit, but there's an egg of this wasp within, and it hatches. It gets bigger and it kills the caterpillar in the process while develops, and out from this caterpillar might pop out one or many of these wasps. These parasitoids can also lay eggs within the eggs of other insects. So this is the 'samurai wasp' (Trissolcus japonicus). One that I spent a few years working on, and it lays a single egg inside stink bug eggs. So from an egg mass of 28 stink bug eggs, you can get 28 wasps popping out of them. So there are about a 100 thousand species of wasps in the world. And most of these are parasitoids. So there's parasitoids that specialize on horn worms. There's parasitoids that attack maggots, parasitoids of aphids, thrips, almost every insect has some type of little wasp that wants to lay its eggs within that other insects eggs or its larvae. [Abby] I'm remembering a picture I saw from my friend's garden last year of a tomato horn worm that had had a parasitic wasp than it was still alive while the eggs where I like hanging out on it and then the wasps all hatched and immediately feed on that horn worm. But it's a pretty, I mean, it's wonderful because horn worms are really detrimental to our tomato plants. But it also just feels like something out of another world. [David] It would make for a great sci-fi movie. Not a good ending for the the insect that's getting killed, but a unique way to control other insects. [Isabel] So we were also curious if you could speak to things that people can do to kind of support is beneficial insects in the garden. [David] Yeah, there are a couple ways to help beneficial insects. So insects need two things. They need food and they need a place to live. So for food, many beneficial insects, if they don't have their host, the insect that they're feeding on or they're attacking. They can also use nectar as a source of energy. So the same types of strategies for helping pollinators can be use to help beneficial insects. So including plants that have nectar within them. And planting different types of native plants that bloom at different points in the growing season. So there are a lot of plants that look nice and keep their color for awhile, like petunias and begonias. But those are almost like a wax apple to a beneficial insect because there's not a lot of energy they can get from that. Those have been bred for showiness often at the expense of nectar production. There are some people that put companion plants which might draw in beneficial insects. There's a fair amount of myth and there's also some truth to that. It really depends on the, on the plant species and how big the system is. So on a commercial scale, putting in flowers around the edge of a field, if you're a farmer, that absolutely is going to. An impact because in a landscape where there's not a lot of places for insects to find food that can be really beneficial. If you're just bringing in one potted plant next to your garden, don't expect that that's going to lead to a dramatic increase. But there are a couple of examples I wanted to share of companion planting that can be useful. So adding a basil near tomatoes can be helpful for reducing thrips and horn worms. Within Brassica crops, things like Brussels sprouts or cauliflower. If you put sage or mint or dill nearby, that can help repel some of the cabbage worms species that on those. And sweet alyssum is another plant that's good to put in your garden because that is a good plant for hover flies. And hover flies are a double bonus for beneficial insects because the hover fly as an adult is a pollinator and as a larva. The hover fly feeds on soft bodied insects. So it's a predator, both a predator and a pollinator. [Abby] And I'm also remembering we had a conversation last year with Kelsey Graham talking about wild bees and wild pollinators and some of the ways to help cultivate them in your garden. And a lot of it was leaving sort of plant matter around for habitat, right? Not necessarily feeling like as soon as, as soon as things turn from your perfect ripeness to a little bit past their prime, not necessarily pulling out plants and removing all that debris. So leaving habitat, does that stay true for a lot of the insects that you're speaking up as well. [David] You're asking about leaving... [Abby] just like kind of leaving more of that leaf matter and that plant material in your garden, rather than striving for that perfectly cleared garden at the end of the year. [David] Okay. Thank you for clarifying. And that's an appropriate question for now, because people are starting their spring clean-ups and wondering what to do. In general, leaving an undisturbed corner or someplace in your garden is a good thing because insects need a place to hide if there's only direct sun, That's not an optimal habitat for most of them, there's beneficial insects that live in the ground and are only active at night. So having some bare soil in an area like in your flower bed and not mulching the whole thing can be helpful or just leaving a patch a little messy because that complexity of habitat can help multiple types of beneficial insects. One comment about garden cleanup is that really there's one type of beneficial insect that is most affected by cleaning your garden too early compared to others, and that will be cavity nesting bees. So I know this is polinators and I don't to want to stray too much into that. But those cavity nesting bees are nesting in the stems of plants potentially. And if you cut down your plants that might have open stems too soon, then you might be eradicating or getting rid of the nest of a cavity nesting bee. But for, for many insects if you're doing light garden work cleaning leaves off the ground, moving brush. It's not likely to have any major impact to a beneficial insect unless you're going deep in the soil a few inches like you're doing early telling because a number of insects do spend the winter either as cocoons or as adults underground because that soil is warmer than the air temperature. So if you're doing a lot of disturbance to the soil, that's something you might want to wait a couple extra weeks more so you don't damage those over-wintering insects. Just working at the surface would not have as much of a negative impact. [Abby] Yeah, it's a really good tip because I know it's like the first few days of above 60 degrees and everyone's pretty eager to get out there and just waiting a little bit of extra time. Because realistically we can't plant anything right now anyway outside, or not that much. Can you give us some tips on noticing damage from non beneficial insects, do you have any tips on how if you're in your garden and observing insects, how to kind of distinguish the ones that are good versus bad. For putting simplistic terms on it. [David] That's a tough one to answer. So often you don't notice them, the bad insects until you see that the damage. So you might see leaves that looks skeletonized and full of holes. Or perhaps the leaf is missing completely overnight, which might happen from larger caterpillars. And the presence of an insect on a plant itself does not mean that it's a pest (or) It's a bad insect. It could just be incidental that it's an insect landing on there or it could be something beneficial. That's looking to hunt. A number of insect pests tend to be small. So things like aphids, thrips, really tiny, microscopic, and there's not a lot of beneficial insects that, that look like them. But the most common types of beneficial insects you'll find in your garden are things like lady beetles or lacewings. You might find ground beetles too. So if you see anything that would fit into that category, generally good insect. [Abby] Yeah. And I think that the tip about noticing where there is damage too, is a good one, right? Because if they're just hanging out and not doing much of anything, they're probably fine to leave alone. And I had a really bad infestation of a bean beetle in my garden last year. And of course, the first sign is all of the leaves kind of turn to that lace. And then you flip them over and you start to see what kind of bugs are there. And then you learn which ones, which ones to maybe avoid the next year. I didn't learn. I kept planting beans in the same place, and having the same bugs, but I did notice some helpful beneficial insects along the way. [David] Crop rotation. Is a good thing to do is when you plant the same crops or plants year after year, the, the pests that feed on them, if they spend the winter in Michigan, we're going to spend the winter near the, in the area near those plants. And once they come out and emerge from the groundwater, that's June, July, August, Like a squash vine borer, To add a human side to it, It'll think "I found some squash again, this is great! I don't have to search elsewhere in the neighborhood for it." But even though I say that, I'm still guilty of growing squashes every year because I like squash. So it is just something to be prepared for. Knowing when some of the pests might arrive and what some of the beneficial insects could be relying on them as a form of natural pest control? [Abby] Yes, or our naive optimism every year and like, "this is the year I'm gonna be on top of it." but it never turns out that way. [Isabel] Abby, I'm kind of happy you didn't get rid of the beams because I got to see that the bean beatle this year because of it. They're very odd-looking little pupae. So David, I know you touched on, don't kill and then ask questions. Are there any other places where people could go wrong? It could be for pest control or when approaching insects in the garden trying to support them. [David] So sometimes there are people who approach me with questions of how do I kill this? What's the best insecticide to use? And I do want to apologize, there's a dog in my neighbor's yard and I can't do anything about... if you hear that... So people will say, what's, what chemical can I use to, to kill this? Or how do I get rid of this insect? Sometimes that is the correct thing to do. If the damage is high enough that if you don't do anything, you're going to lose your plant. There's something called an, an economic threshold. There's a level at which if you don't do anything, then there's going to be a lot more damage and it's going to cost money. Usually we apply that to people who are growing food for, for farm sale or for commercial growers. But that can apply in your home garden too, because after a certain stage, if you let the plant go too far, you're not gonna get any fruit, you're not gonna get any foliage that, um, that you can, can eat. So the first one thing to know is preventative strategies for stopping the pests in the first place. And that might involve floating row covers. So you keep the pests away from the, the plant, rather than giving them easy access to the plant or just knowing what is out there. So it's very hard to say I can guarantee this beneficial insect will come and feed on a pest. Do x, y, and z, because it all depends on what the conditions are. Some insects are able to move a mile or two or more. There are some like these tiny parasitoid wasps that may only move a 100 feet a day maximum. So if you don't have if you have a big yard and you have a small garden, and it's just surrounded by a quarter acre of turf grass, for instance, it's going to be tough to, to draw in beneficial insects. So keeping habitat that has native plants or has plants with nectar and an area for these beneficial insects to stay when they can't find, find their food that they want to feed on is something that's most critical. [Abby] So we are wondering if you can share some tips on overcoming fear of insects. So I know a lot of folks have just kind of that knee jerk Like it's a, it's an insect, it's a bug, kill it, reaction. And maybe some kids to do you have any tips for how you built a better relationship with insects or how you've seen kind of folks overcome some of those fear reactions? [David] You know, if you can start young, don't only read books that portray negative things about insects. And so I have two young kids at home. as I read a number of their books, there's actually a lot of insect characters that are doing good in their book. So it's nice to see that portrayed. And when you see something out there, instead of the, the ick factor, maybe step back a bit and observe what it's doing. Because the vast majority of insects in our communities are not out to hurt us. Mosquitoes might be one exception because that's how they feed. But we'll leave mosquitoes out of the question. Most insects just want to eat another insect or they wants to eat a plant. They don't want to hurt people. They don't pose much of a risk to us. And that's true for those big cicada killer wasps or other large wasps that we have an area too. So I take a lot of risks because I'm an entomologist, I want to see things up close. So when I see a cicada killer, the first one of the season, come and try and catch it in a jar. Not something that I would recommend necessarily. But if it's something that doesn't sting, you know, catch it in a vial or jar to get a closer look at it to see what it actually looks like. Because we have a number of insects that really beautiful and have iridescent colors. But you might not notice until you look closely to them. So learning what it is about what's in the area. And if you are around someone who is very anti insect, maybe trying to understand more, you know, you, you said that this is nasty seeing this bug, but what's so nasty about the aphid on the plant? From the perspective of the plant. Yeah, it's bad for the plant. But wow, why is it so bad? Because some people do have phobias and not a mental health professional. I can't cure those. Um, but when people learn more about why insects are in an area and what they're doing and that they're not a direct threat to us, for the most part. I think it leads to better understanding about that. Another trick that'll be really cool if you become somewhat of an expert in bees is trying to pet a bee... So one thing about these is that only the females stain. So if you reach a level where you can distinguish between a male and female, and that is possible to distinguish them just with your eyes going out and trying to pet especially bumblebee, the very soft and fuzzy. Now I take the risk and do it with some of the females because they're for the most part they're really docile. They're not likely to sting you unless you ground them and trying to harm them. But they might be in a plant. And just like some people like to pet dogs... I'm a strange entomologist that likes to pet bees. [Abby] I try to pet the praying manti in my garden but they don't they don't let me get too close. They get up and go into attack position so I can understand that eagerness to pet And I also feel like we need a disclaimer here to get to know b is before you try and try and to pet them too much! [David] I would agree with that. So beatles, lacewings. Lot, a lot of insects don't sting or harm. Yes, wasps and bees, Be very careful, but it's a really cool party trick if you, if you want to do that. [Abby] I'm trying to imagine what parties that would occur at, but with COVID, we're in wierd times. [David] socially distanced, outdoor parties with flowers. {Isabel] Yeah. I got you. "I'm petting the BEE". [Abby] Yeah. I think one of the things that has helped me on this last year is just slowing down to observe, like you said earlier, being in a space last year when I was just sending a lot more time in my garden and just observing insects in general do their natural things. You start to see them like hop and do, do cute, if I daresay, cute and interesting things in the garden. And that helps build a different relationship with them because you see them as more than just this hard shelled, creepy-crawly. You see them as like, oh, "you have your own quirks and characteristics and like ways of surviving in the world." [David] Yep, and the way that insects move is another good way to distinguish them. So that when you think about it, when you said hop, for example, grasshoppers and crickets, they have very big legs. On their hind legs, the back most one, whereas praying mantises, they have very big legs in the front. So different features of insects or the length of their antenna up the two things on their head can be a way to, to distinguish them very easily, right when you see them. Yep. [Isabel] So David, do you have a favorite insect? [David] I do. And I made sure to put up a picture of it because I think it's a really cool one. So let me bring it up one more time. And this is an insect that is probably found in every single community in and Michigan. Despite the fact that this picture is from Missouri. This is a Virescent Green Sweat Bee. so scientific name Agapostemon. That's the genus. But this is a tiny bee that visits small flowers including weeds, things like chickory, dandelion, asters. And it's this shiny green bee, that you'd think. This has to be something tropical, but we have it in Michigan in almost every habitat. From a vacant lot in the inner city to a lake side up North, or a suburban area, or on the side of the road, you will find green bees in almost every place in Michigan, really common, really beautiful bee. [Isabel] I do appreciate that iridescence. it reminds me of tiger beetles, I think they're called, which is like one that I always like, "Oh, I want to get a closer look" and then you have to run and then they move quickly. And I want to chase them. And we have a tortoise beetles as well. And there's dog bane beetles which are really colorful. So there's a couple different types of beetles that are, are shiny and, and cool. [Abby} So I think this is a good transition plan to answer some of our audience questions. It's that's good with you, David. There are so many questions. Somebody share the need for birds to managing insect populations and not just jumping to killing them because they are part of such a larger food system and web. So I appreciate that reminder. We had a couple of questions about timing. You mentioned some of the like pausing to clean up yard debris and some of those those hollow stem things. I'm wondering if you have any tips for when might be the right time to start cleaning up your old tall grasses and cleaning up debris. To kind of both support growing in your garden and support beneficial insects populations. [David] There's not a, a set date. That's best to do that, but there are two things I'll comment about that question.