- Hello, everyone.
My name's PJ Liesch
and I'm an Extension entomologist here at UW-Madison,
and the director of the UW Insect Diagnostic Lab.
Thanks for joining me today.
I'm excited to be talking about insects
in home gardens and ways that you can manage
and deal with those pests,
but also reduce impacts on the environment
and protect beneficial organisms in our garden,
such as pollinators and predators and parasites
that may be helping control those pests.
Now, there's two main things I want to talk about today.
The first is how to actually scout
and look for pests and problems in our garden,
and as well, discuss some resources
to help you identify those insects that you do find.
The bulk of today's talk, though,
is gonna focus on the second bullet point,
which is how to manage insect pests in our garden.
And the main take-home message I will mention up front
is that there's a whole bunch of different techniques
that you can use, but you really need to tailor them
to your specific gardening situation.
What I mean by that is some folks have big gardens
that might be a couple hundred square feet,
other folks may have small raised bed gardens
that are only five by eight or some similar size to that.
And so that's gonna impact the amount
of resources you can use
and the techniques that you can use.
You also have to think about the amount
of free time that you have.
If you work a 9:00 to 5:00
and can only spend time in your garden on the weekend,
that's very different than someone who might be retired
and can spend an hour or two in their garden every day.
And that's gonna influence the types
of management approaches that we can use.
Now, two things I just won't have time to talk about today,
how to manage and deal with specific insect pests.
That's just beyond the scope of today's talk.
Rather, I'm gonna focus on, very broadly,
different management techniques.
I also won't have time to get
into discussing specific plant care scenarios.
Now, before I discuss today's topics,
I do want to introduce a couple of really helpful resources.
And today's talk is really based on this book on the left,
IPM for Gardeners by Ray Cloyd,
Phil Nixon, and Nancy Pataky.
This is a relatively new book.
And if you're interested in the overall theory
and practices of managing pests in gardens,
this is an excellent book.
A lot of good details in there.
And again, today's talk is kind of
a condensed CliffNotes version of that book.
So if it interests you,
I'd encourage you to track that one down.
Otherwise, if there is a single book to purchase
to help you identify and understand the insects
in your garden, I would highly recommend this book
on the right, Garden Insects of North America ,
by Whitney Cranshaw and Dave Shetlar.
This book is several hundred pages long,
it's loaded in color photographs
and important details about how to identify
and understand the biology and life cycles
of insects found in gardens and yards in general
because this book does also discuss insects
that are found in trees and shrubs as well.
So really a great resource.
There's also a chapter to help identify
and understand beneficial organisms.
Here at UW-Madison Extension,
we do have a number of really helpful resources
to help you out in your gardening,
with your gardening goals.
The first is our website, hort.extension.wisc.edu.
That website serves as a repository of all sorts
of informational fact sheets that discuss insects,
diseases, general horticulture topics, and so on.
But also on that site,
there is a way that you could submit gardening questions
and get them answered by an Extension expert.
So you can submit your name, your question.
There is even a way to upload photographs
that will get sent to someone in Extension,
who will get back to you
and help you out with your gardening questions.
Now, when it comes to your actual garden
and finding those insects,
the single most important thing you can do is scouting.
That means you're going out, looking for the insects.
If you don't spend a whole lot of time in your garden,
it may seem like problems pop out of nowhere.
But in most cases, those problems have been present,
kind of smoldering at a low level
and maybe increased over time.
So the way to do this, to look for insects,
is going out and doing visual inspections
and looking for clues that something may be amiss.
That may be holes in leaves or notches in leaves.
It may be discoloration or distortion of plant tissue.
And we'll talk more about those clues
and what they could mean in some of the coming slides.
In terms of timing, when and how often to do this,
ideally, if you could do it daily, that would be excellent.
I realize, though, many of us
have realistic time constraints due to family matters
or work and things like that,
and we might only be spending time
in our garden on the weekends.
And that's perfectly fine too.
But if you can scout at least once a week
or more frequently, that's really helpful
so that you can stay on top of what's going on
in your garden.
A couple of really basic tools can also be very helpful
to look for and identify insect pests in your garden.
One of my favorite tools
is a magnifier commonly called a jeweler's loupe.
If you went to a jewelry store,
they may use these to look at diamond rings
and things like that.
This is basically a magnifier
that has about a 10X magnification.
Really helpful identifying insects
and scouting purposes as well.
Another thing that can be helpful is a flashlight.
And the reason I say that is many of our insects
are active during the daytime,
but certain insects are primarily nocturnal.
They may feed or be active almost exclusively at night.
And if we look for 'em during the day, they may be hiding.
And so if you see something going on in your garden
and you suspect insects are involved, but can't find them,
it may be worth the effort and time
to go out after dark with a flashlight and look for them.
And then, lastly, one other tool that can be helpful,
you're gonna bump into insects
that you just aren't sure what they are,
and it's really handy to have some sort of Tupperware
or other small container on hand,
so you can put the insect in there
until you can identify it.
That way you can take some time, dig into those resources,
and figure out is this insect a friend, or is it a foe?
Now, before we get into the details of managing insects,
it's really important to understand a few basic details
about insect anatomy.
And that is their mouth parts
because that's how a lot of insects interact
with our plants.
They use mouth parts to feed on those plants.
Now, there's two main types of mouth parts
that we see in plant-feeding pests.
The first type is chewing mouth parts.
And these essentially function like a pair of pliers
or a pair of scissors.
So that's the tool that they have
in the toolbox, so to speak.
When they use these mouth parts,
they're gonna be physically cutting
or tearing away pieces of plant material.
As a result, we may see holes in leaves
or notches in leaves, or in some cases,
the leaves could be gone entirely.
Now, why is it important to understand this?
There will be cases where you're gonna go out
into your garden and the insect may be gone entirely,
or it may be hiding and hard to find.
We can look at these clues
and work backwards to try and figure out
who done it in these types of cases.
And so when we see holes and notches
and other indicators to show us
that it's an insect with chewing mouth parts
in a home garden,
that almost certainly is going to be either a caterpillar
or a beetle of some kind.
So we can start to narrow down our search
and figure out the culprit.
There are a few other pests from time to time that pop up,
like grasshoppers and slugs and things like that,
and even earwigs and sawflies,
although those tend to be less common
in home garden setting.
Another type of insect mouth part
are sucking-type mouth parts.
So these are tubular structures
that essentially function like a hypodermic needle
or a soda straw.
They're essentially restricted to a liquid or fluid diet.
So they suck fluids from plants.
And these insects couldn't chew holes
in your plants if they wanted to.
They just don't have the right tool
in the toolbox to do that, when you think about it.
So when they suck fluids out,
what are the symptoms and clues that we see?
We tend to see discoloration or speckling
or sometimes distortion of plant tissues.
So again, we sometimes have to work backwards,
look at these clues,
and try and figure out what insect caused the damage.
Now, with sucking-type mouth parts and these symptoms,
it can sometimes be vague.
And these symptoms can mimic other conditions as well,
such as drought stress or fertilizer stress
or herbicide drift.
So if you see symptoms that look like this,
you can't assume it's from sucking insects.
You would need to do some additional detective work
to really get a better idea of what's going on.
Now, if insects are involved, there's one particular group
that entomologists call the true bugs,
the order Hemiptera.
These are things like aphids, plant bugs,
stink bugs, squash bugs, leafhoppers, and so on.
These all have these sucking-type mouth parts.
A few other pests that we see pop up from time to time
in home gardens would be spider mites and thrips.
Also can cause damage that looks a lot like this.
So again, the most important step in your garden
when it comes to scouting and pest management
is to look for and scout,
and then identify the insects that we have found.
In my mind, once we've done that,
the battle is half over.
Because once we know what the insect is,
it's very easy to look up some of those fact sheets
or other online resources, or dig into some of those books
to learn more about the particular insect.
We can learn aspects about their life cycle
and their biology.
Is this a minor pest, or is it a significant pest
that you really need to be worried about?
Is it something that we might see again next year?
But unless you identify the insect you're dealing with,
it's very difficult and may not be possible
to answer many of these questions.
Now the rest of the talk is gonna focus on managing
and dealing with these pests.
And there's really a bunch of different approaches
that we can use.
And I like to think of these approaches as a pyramid.
We have at the base of the pyramid
a lot of preventative things that we can do.
We call these cultural approaches.
We also have a lot of physical
or mechanical control tactics that we can use.
We can rely on biological control.
And then up at the tip-top of the pyramid, chemical control.
And remember, today's talk is focusing
on reducing environmental impacts
while we're managing pests in the garden.
So very similar to our food pyramid,
we should be using chemical controls
only as needed and sparingly.
So there's lots of other things
that we can do to help manage or prevent pests outright,
so that we don't get to that point
where we need to use chemical pesticides.
Now, again, just a reminder,
I'm gonna show you a bunch of different approaches,
and you really need to take these approaches
and tailor them to your specific gardening situation.
The size of the garden,
how much free time you have on hand,
and other factors as well might make some
of these approaches more feasible for you than others.
So let's talk about cultural practices.
These are basically ways
that we can modify the local environment,
and we can make some decisions
and do some planning to help us out.
So there's a lot of things I'm gonna be talking about
separately when it comes to these particular topics.
And first and foremost, one of the most important things
is really understanding the history of your garden.
If you have been gardening
for several years, you'll realize
that you have seen certain problems pop up year after year.
And keeping a gardening journal can be really helpful
in understanding these patterns that you see.
So that can involve maybe sketching out a map.
That way, you have a better understanding
of what was planted where and when.
But also keeping notes on what type of insects
and pests and diseases that you saw pop in your garden.
Looking back over time, that can help you understand
these patterns better and better.
So this is an invaluable approach
that can be helpful for planning purposes
in your own garden.
Also, there's a lot of decisions that we can make.
And many of these decisions for planning occur
in January, February, March, and April,
before we even started planting things outside
in our garden.
Some of these considerations, picking the correct plants.
If you look at the climate in Wisconsin
and plant hardiness zones, the climate in Kenosha
and southeastern Wisconsin is very, very different
than northwestern Wisconsin.
So make sure you pick plants
that are suitable for your growing zone.
Just as an example,
if I told you I wanted to grow bananas out in my garden,
you'd probably give me a weird look
because I'd be setting myself up for failure.
That's just a plant that isn't suited
for our climate here in Wisconsin.
So pick plants that are suited for our climate.
Also, look back over time and think,
have you bumped into particular problems before
with an insect or with a disease?
Sometimes you can dig through those seed catalogs
and find varieties that may be more resistant
or tolerant to help avoid some of these problems.
So again, these are decisions we're making ahead of time
that can set the stage and help prevent issues.
Some other things to keep in mind:
Planting at the correct time and timing.
So make sure to read those seed packets.
They have valuable information there to let you know,
should those seeds be started inside or outside?
Before frost or after frost?
Do those crops do better in cool conditions
or warmer conditions later in the summer?
So keep that in mind,
and make sure to heed that information
that is on the seed packets.
We also wanna put plants in the correct spot.
So again, read the seed packets
and understand, is that a crop or plant
that needs full sun, or can it tolerate partial shade?
And depending on your yard and situation,
you might have to make some decisions there.
Also keep in mind that certain plants are different sizes.
And so if you have corn
on the south-facing part of your garden,
or south part of your garden,
that may shade out things to the north of it.
So we do have some considerations to make there.
And then also understand the correct spacing.
This is a challenge, especially for new gardeners.
We sometimes put plants too close together.
And spacing can really pose some challenges
for us in the garden.
Our plants are competing one another.
We can inhibit airflow, which might incur diseases.
But from an insect standpoint,
if the plants are really crowded together,
it makes it harder to scout for pests
and identify 'em when they are there.
So by having the correct spacing,
our plants are generally gonna be happier and healthier,
growing more robustly, and it makes it easier for us
to scout for and look for problems
before they really start causing significant headaches for us.
When it comes to watering and the soil and fertility,
the mindset I like to think about is Goldilocks.
Not too much, not too little.
We want things to be just right.
So make sure you're using good watering practices.
If we have a year like 2021
where the summer growing season was quite dry in many areas,
make sure those plants are getting appropriate amount
of water so that they aren't stressed because of that.
But likewise, if we have a very rainy year,
we don't want to be overwatering our plants either.
That may cause some problems.
So use generally good watering practices.
From a disease standpoint,
we don't want foliage on those plants
to remain wet for too long either.
So make sure you're watering things properly.
In terms of the soil, in some situations,
we may have control over the soil
that we can pick and choose,
such as with raised bed gardening.
But if you have a large garden,
it's gonna be quite difficult to modify
or change that soil outright.
It may not be feasible.
And some of you may be doing straw bale gardening,
where soil is out of the equation entirely.
So everyone's gardening situation
is a little bit different.
But if you're using soil or potting mix,
make sure to get a soil test.
That helps you understand what's there,
what are the properties of that soil,
and what is the nutrient profile like.
You might find out that your soil
is perfectly fine as is,
and you don't necessarily need to add any fertilizer.
That's important and invaluable information to know
because if we apply too much fertilizer,
that can actually have negative impacts
from an insect point of view.
There are certain creatures like aphids
and spider mites that can thrive on overfertilized plants.
So again, think Goldilocks.
We want these things to be just right in the middle,
not too much one side or the other,
going to the extremes.
Some other considerations
that are cultural practices would be crop rotation.
So certain insects or diseases may keep popping up again
and again over time, unless we rotate.
We can rotate both in space and time.
If you have a large garden, for example,
you could take corn from one side of the garden
and plant it at the opposite side the following year.
That can be helpful.
If you have a smaller garden
where you can't move things terribly far,
it may be more helpful and feasible to rotate over time.
So you could skip a year or two for a particular crop,
and then come back to it at a later stage.
So this can be really helpful for certain insect pests,
but also diseases as well.
And some important crops
to consider rotating would be things like corn.
We have a particular insect, corn rootworm,
that can really cause root damage extensively
if corn is planted in the same spot year after year.
But other crops can benefit as well.
Cole crops, brassicas like kale and broccoli,
solanaceous crops like tomatoes, potatoes, eggplants, and so on,
and then cucurbit crops like cucumbers
and squash and things like that can benefit
from rotation over time.
And then last for cultural practices is tolerance.
It turns out that a lot of plants can tolerate quite a bit
of insect damage before yield is actually affected.
So keep that in mind.
If you're a new gardener, you may not have a stomach
to tolerate a whole lot of insect damage,
but realize some plants are really pretty robust.
So think about beans and Japanese beetles.
It turns out Japanese beetles can defoliate
about 30% of the leaf area of bean plants
and yield will not be affected at that point.
So you'll still have the same number of bean pods,
and they'll be just as big.
If we get more damage than that,
then yields are gonna start dropping
and we won't get as much of a bounty
from our garden that year.
But we can tolerate some fairly low
to moderate levels of feeding activity.
Now, we also have keep in mind the parts of the plants
that we're concerned about.
If we are concerned about tomato leaves,
you know, I may be able to tolerate some damage,
but if the insects are feeding directly
on the developing tomato fruit,
I'm gonna draw the line in the sand at that point
and probably intervene.
Also, we need to be aware that sometimes insects
and plant diseases can interact with one another.
So a good example would be cucumber beetles
and a disease called bacterial wilt.
It turns out that cucumber beetles can carry
and transmit that disease.
And they might only be present in low numbers in your garden
and causing a little bit of nibbling here and there,
but if they transmit that disease,
that could be headaches for us later on
in the growing season.
So you really need to understand the crops in your garden,
and also the pests that you're dealing with.
That's gonna influence how much damage we can tolerate
from those particular insects.
Now let's talk about physical or mechanical control.
So these are things like handpicking and squishing
and blasting insects like aphids off
with a stream of strong water.
We have some options here.
And these do not involve a chemical pesticide.
So these are any physical activities we can do
to deal with pests or help prevent them.
And we'll talk about these in more detail.
So first and foremost,
getting good weed control can be really helpful.
So if you have a smaller garden, handpicking or hoeing
or using other tools can be very helpful.
And the reason for that is weeds can do a number
of bad things in our garden.
First and foremost,
they directly compete with our crops for nutrients.
So if we take them out of the situation,
that means that our carrots
or tomatoes or other plants are growing.
They can get those resources
and it's not being taken away by something else.
Some other things that are important to keep in mind.
Increasing airflow from a disease standpoint.
If we have a bunch of weeds growing in our garden
and we don't have as much airflow,
that could cause some issues.
From an insect standpoint, if we get the weeds out of there,
it can make it easier for us to scout and look for problems.
So that can be very helpful.
And then, lastly, weeds can sometimes serve
as a reservoir of insect pests and diseases.
And so if we eliminate those from the situation,
that can really help us out.
Couple of other things to keep in mind along these lines.
We can sometimes use mulches
and other ground covers to help us suppress weeds
and help us prevent issues like this in our garden.
Some other physical and mechanical controls we can use.
We can do things like handpicking,
or knocking insects into a container of soapy water,
even just squishing them,
if that doesn't make you too squeamish to think about.
What's nice about these approaches
is they have an immediate impact
because you are taking one insect out of the situation.
However, keep in mind that handpicking
in these approaches don't have any residual protection.
So, for example, if you're picking Japanese beetles today
and it's 9:00 AM, well,
more beetles could fly in in the afternoon.
So you do have to understand the pros and cons
and strengths and limitations
of all these different approaches
and tailor them to your specific gardening situation.
Now, this technique is also best for insects
with limited mobility.
If you have tiny insects or things that are highly mobile,
it's simply going to be hard to grab them by hand.
To help out with that, sometimes it can be helpful
to have a container of soapy water
that we can hold underneath the insects,
and then tap them down into that container from above.
So for cucumber beetles and Japanese beetles
that like to tumble down or fly off when disturbed,
that can sometimes be pretty helpful in that regard.
Now, some good candidates for handpicking,
again, things that tend to be larger, less mobile.
So caterpillars this can work very well for,
certain beetles.
I do this in my own yard for Japanese beetles.
And in my own garden, it works pretty well.
If I can do that on a daily basis,
that can actually help out.
But again, anything that's a little bit bigger
or a little bit slower.
It's not gonna work well
for tiny things like aphids or rapidly moving insects.
We also can use this approach for insect eggs in some cases.
So if you train your eye to look for the eggs of pest species.
And as an example,
I show in the bottom right-hand corner some eggs
from squash bugs.
If you were to look for those while scouting
and you find 'em on the undersides
of cucumber or squash leaves,
you could take your thumb and squish those.
And by doing so, you've just taken 15 or 20 insects
or future insects out of the equation.
So you've done something
to help prevent issues down the road.
Some other physical and mechanical approaches
that we can use; we can use barriers.
So this is netting and row covers, things of that nature.
This is gonna create a physical barrier
between the insects and those plants.
If the insects can't physically get to your plants,
they can't cause damage to them.
So we can use screening and mesh netting.
Sometimes we can actually find larger mesh sizes,
which we use to deter birds and mammals
and things like that.
But for insects, keep in mind, we do need a fine mesh size
'cause many insects are relatively small.
So some considerations with this, though.
We have to keep in mind the size of the plants.
It's gonna be easier to cover low-growing plants
that don't get terribly tall.
We also have to consider pollinator access.
If we have plants that produce flowers
which require bees or other pollinators
to visit to actually produce our crop,
we're gonna have to take this covering off
so that pollinators can get access.
And then also there's the aesthetic side of things.
If you are growing particular plants,
such as flowers, purely for the aesthetic aspect,
it kind of defeats the purpose
to have them covered up with a sheet.
Or maybe if there's a peak period of pest activity,
you could consider covering them
just during a certain window of time.
Some options and plants where this might work well for:
things like leafy greens, seedlings, and transplants.
Sometimes these row covers can actually work somewhat like
a greenhouse, so they can help extend
the growing season earlier and later in the year.
And there are some other situations.
If we have crops that don't require pollination at all,
such as herbs,
sometimes row cover can be a really simple option
to help prevent insect damage.
Some other mechanical and physical things we can do.
In certain cases, we can use traps,
but it's always important to think about
what those traps are going to do.
Are they going to catch insects,
or are they actually providing meaningful control?
Because that doesn't always happen together.
There are plenty of traps that will catch insects,
but have no impact on the damage that's occurring to the plants.
And sometimes traps can actually backfire,
and you get more damage if you use that.
We'll talk about an example here in a second.
So we have to think about traps, are we using them for monitoring
and scouting versus control?
Sometimes they can help out for different purposes.
In other cases, they may not help at all.
So think about Japanese beetle traps.
And if you're a home gardener,
you see these all the time at hardware stores
and garden centers.
They sell like hot cakes sometimes.
But several research studies have found
that if you use Japanese beetle traps,
it actually draws more to the general area
and you end up with more damage on nearby plants.
So yes, those traps catch a lot of beetles,
but you get more damage overall.
So we actually discourage gardeners
from using those particular traps.
There are situations, though, where traps may make sense.
If you grow apple trees,
we have these red sphere traps that can be useful
for monitoring or control
if you just have one or two apple trees.
In home gardens, we can use harborage, or hiding traps,
maybe an old board or shingle,
that we can put down on the ground.
And if we have insects or creatures
that like to hide during the day,
such as cutworm or armyworm, caterpillars or slugs,
they may seek shelter during the daylight hours
under those objects, which we can flip over,
and then squish or pick 'em up
and throw 'em into a container of soapy water.
So we can use tools like that to help us out.
We also have some sticky card traps
which can be useful for monitoring
for small insects like aphids and thrips and so on.
So we do have some traps out there can help,
but keep in mind,
read up on the particular traps you're trying to use
and see if they will accomplish the goal
that you're trying to accomplish.
Then remember from the pest control pyramid,
we have some biological control options.
And this basically means relying on the good guys,
relying on Mother Nature
to take care of the problem for us.
So that involves insect predators, insect parasites,
and in some cases, there are actually
beneficial disease pathogens
that specifically attack and kill insect pests for us.
Now, there's really two main ways
we can go about doing this.
One is not really feasible for us.
The other one is really quite feasible in most situations.
So the first is direct intervention.
This is where we would directly add beneficial predators
or parasites to the equation.
Unfortunately, this isn't really feasible
for home gardens here in Wisconsin.
We can't run down to the garden center
or Target or Walmart and buy a box
of 10,000 lady beetles or lacewings.
And if we did release them,
because there are sometimes companies online
where you can order such beneficial insects,
in many cases, they may fly away or otherwise disperse.
That approach can be much more effective
in a greenhouse setting where the beneficial insects
will be contained and will be forced to feed on the pests
in our particular area.
But outdoors,
that generally has limited effectiveness overall.
However, the second approach can be quite helpful.
This is the more indirect route,
where I think of it as the Field of Dreams approach.
If you build it, they will come.
We can create habitat around us
that will draw the beneficials in,
and then they can help us out in our garden.
And the key way to do that is
to diversify the landscape around you
with a wide range of flowering plants,
because it turns out many beneficial predatory
or parasitic insects that can help us out
will be drawn to different types of flowers
to get nectar as a fuel source.
And then they may hang out in the general area
and help control and feed upon pests in our garden.
Now, also, it's really helpful to understand
and be able to identify beneficial insects.
So I'd like to draw your attention
to the publication in the upper right-hand corner.
And you can find this publication
via that short link in the upper right-hand corner,
the Bitly link.
This is an Extension publication which is over 100 pages long.
It's freely available as a PDF,
or hard copies are available for purchase for $12.
And this book is loaded with colored photographs,
and it explains the biology
and benefits of having these beneficial predators
and parasites and pathogens around your garden.
It also discusses ways that you can encourage them
in the landscape around you.
So if this interests you,
I'd strongly encourage you to track down that publication.
Also, the garden insects book I referred you to
earlier by Whitney Cranshaw and Dave Shetlar,
that has an excellent chapter discussing beneficial insects
that you're likely to bump into out in your yard.
So recognize the good guys,
because if that's all we're finding,
or they seem to be taking care of the pest problem for us,
we don't want to spray and take out the good guys.
So keep that in mind.
And biological control can be quite successful
under the right conditions.
And then just to finish up,
I want to talk about chemical control.
So remember, this is at the top of the pest management pyramid.
We want to use chemical control sparingly
and only if needed.
Now, there's two main types I'll discuss briefly.
We've got biorational pesticides and also conventional ones.
It's important to keep in mind that each product
has a different personality, if you will.
They differ in how long they last,
how long you have to wait before you can harvest,
the types of insects that they control, and so on.
And just as a disclaimer,
I will be showing some ingredients and also products,
but this is not an endorsement.
These are being included for educational purposes only.
And always read and follow all the directions
on the pesticide label.
So we have biorational products.
These are generally based
on naturally-occurring products or sources.
So often plant-based, but not always.
Many of these are gonna be approved for organic gardening.
And in general, they tend to be less toxic
than our synthetic conventional products.
And in many situations, they don't last as long.
And we have a number of options out there.
I'm gonna discuss the pros and cons of these here
in a coming slide.
We have insecticidal soaps and oils, pyrethrin, spinosad,
and also Bacillus thuringiensis, or Bt,
which is a bacterial-based product.
Then we've got our conventional insecticides.
So these are synthesized in a lab or manmade.
However, they can be based
upon naturally-occurring products.
So pyrethroids are based
upon naturally occurring pyrethrins, for example.
Now, in general, these tend to be a bit more potent
than those biorational and organic products,
and they tend to last longer, in many cases,
for several days to maybe a week or longer,
depending on the situation.
And these are generally broad spectrum products,
meaning they can control pests,
but they also have the possibility
of harming beneficial organisms too.
So we really wanna reduce the usage of these
if we're trying to reduce overall impacts
of our gardening practices.
And there's two main ones you'll bump into
at the garden center.
That would be the product Sevin.
The older formulation contained carbaryl.
And then there's a whole bunch of products
that contain pyrethroid ingredients.
These end in the letters T-H-R-I-N.
So permethrin, bifenthrin, cyfluthrin, and so on.
They all work very similarly against the insects.
And then just to wrap up by discussing some of the pros
and cons of these different approaches,
I have a table here to summarize some of the main points.
So we see that some of the biorational products,
like soaps and oils, really only work by context.
You have to spray insect pests thoroughly.
The soaps and oils primarily work against soft-bodied
or squishy insects like aphids, caterpillars, and mites.
And they basically work until they have dried,
which can be a very short period of time.
If it's a hot, sunny day,
that might only be about 10 to 15 minutes.
What's nice about these is a trade-off.
They have a short harvest interval,
meaning that you can spray and use these products,
control aphids or small caterpillars,
and you could harvest those same plants later that same day.
We have pyrethrins, which come from a natural extract
from certain types of Chrysanthemums.
These only work by contact,
but they can work against a very wide range of insects,
which unfortunately means they can pose risk
for beneficial insects, too.
The good predators and parasites.
They break down rapidly, though, usually within a day,
and they have a short harvest interval.
So we could use it today
and be able to harvest our products tomorrow.
But again, always read your product label
for those exact details.
Then we have spinosad, a bacterial-based product.
Works by contact or ingestion,
and it has some residual activity.
It works for several days.
So we could spray this on a plant,
an insect could show up a while later and ingest it,
and it would be controlled.
Now, spinosad works best against chewing insects,
such as certain beetles, caterpillars,
and leaf miners, and so on.
The harvest interval, though,
does vary depending on your crop.
Sometimes you might have to wait up to a week
before you can harvest.
Then we've got Bacillus thuringiensis, Bt.
This is an ingestion insecticide,
so it has to be consumed by the insect.
So we can spray down the plant.
The insect will have to nibble on it
to consume it and ingest it, and it works on their gut.
There's two main strains, though,
and you have to pick these carefully.
Bacillus thuringiensis kurstaki works only
against caterpillars.
It's a very narrow spectrum product.
Bt galleriae works against certain beetles,
such as Japanese beetles.
There's usually generally some decent persistence,
several days, maybe upwards of a week.
And luckily, these products are very specific
to insects and essentially harmless
towards humans and other mammals,
so they have a very short harvest interval.
You can essentially use them and harvest later on
that same day in many cases.
And then those conventional products,
these work both by contact and ingestion.
These have a broad spectrum of activity,
meaning they could pose risk to beneficials,
as well as helping control the pests that we want.
They tend to last longer,
usually several days to maybe a week or longer,
depending on the conditions.
And also, that harvest interval varies.
So again, each insecticide product has pros and cons,
and you have to make some decisions
based on your particular desires.
If you want to do no pesticide versus organic
versus conventional and so on,
but you have to pick and choose wisely.
But again, with pesticides,
we wanna use this from the very top
of that pest management period as a last resort,
and use them sparingly because as I discussed,
there's lots of other things that we can do to help prevent
and minimize pest problems in our gardens.
And with that,
I'd like to thank you for your attention today
and joining me as I talked about managing insect pests
in your garden while reducing impacts
to beneficial creatures and the environment.