Potato beetles showed up in my garden this year, and I was ready- here’s what I did to get rid of them organically and naturally without harmful pesticides… and it actually worked!
Did you know that potatoes are on the Environmental Working Group’s “Dirty Dozen?” This is the top twelve produce items with the most pesticide residue on them- the ones you should always try to find organic. We like to keep a good stockpile of potatoes for fall and winter (because french fries), so growing them ourselves successfully without harmful chemicals is important to us!
When I was a little girl I had a bug collection. I was a full-on geek bug collector with styrofoam and bugs with needles pinned on it and everything. Now I’m in my thirties and loathe the little things. Not sure what happened there… I used to willingly touch them, but now I thrash and scream when one lands on me.
Perhaps my least favorite bug is the Colorado Potato Beetle, and that is because last year they absolutely decimated my prized potato plants and left us with but a meager potato harvest. Plus their larva are so very gross-looking. Disgusting. The things that nightmares are made of.
One day I walked out to the garden to find the plants covered with adult potato bugs, eggs, and every stage of larva in between. It was like a scene from one of those infomercials where they tell you we’re destroying the rainforest at an alarming rate and show clear cut trees with excavators and bull dozers running all around… except in my potato patch.
Well not this year! I WILL be eating homegrown potatoes! Basil Butter Roasted Potatoes? Yes!!
Here’s what I’ve done to win against potato bugs naturally, organically, without harmful chemicals, and without a ton of labor. A little bit of labor, but not unreasonable.
Be Proactive and Be Prepared
From the time your potato plants come up, take a couple minutes every other day to walk the rows and scan for adult potato bugs and watch for holes eaten out of the potato leaves. It’s infinitely easier to control potato bugs if you can catch them when they first appear. I lost my crop last year because I wasn’t paying attention and was blind-sided. Plus I didn’t realize just how much damage they could do.
Controlling potato bugs involves three main steps: physically getting rid of the adult beetles, removing leaves with unhatched eggs, and using an organic bug killer to kill any baby potato bugs that hatch.
Understanding Potato Bugs
If you’re going to kill something, its nice to at least know a little bit about it and also about what you’re using to kill it. Running to the hardware store and buying the first bottle of whatever bug spray you see that will supposedly kill potato bugs isn’t good gardening practice. Understanding just a little bit of bug biology and behavior takes the mystery out of things and makes them so much easier to treat for. Using this information, we can naturally and organically control them, without the use of heavy pesticides.
I See a Potato Bug, Now What?
Game on. Initiate Potato Bug Control Plan. By the time you see one adult potato bug, there are probably more and they’ve probably already laid eggs.
Adult potato bugs overwinter in the ground, and when temperatures warm in spring they climb their way out of the earth and find the first potato or other nightshade family member they can. When do potato bugs first appear? About the same time potato plants sprout and emerge from the ground. Naturally. As soon as your potatoes are up, start watch.
How to Remove and Kill Adult Potato Bugs
I wear gloves because potato bugs gross me out. If there are a lot of them, things will go quicker if you carry a tin can of soapy water to throw them into. Just pluck them off and drop them in. Karl has many memories of helping his grandparents pick potato bugs off rows and rows of plants and putting them into a tin can filled with gasoline.
If there aren’t many I just pick them off and squish them real good with a nearby rock or stick. And then I wave my finger in the air and shout, “let that be a lesson to you all.” This step will definitely help with the control of your potato bugs.
Searching for adult potato bugs is something I do almost every single day, sometimes multiple times per day in the first couple weeks once they’ve showed up for the year. They are large and easy to see- it’s super quick to do, doesn’t require bending over, and will save a lot of time and effort later since one potato bug can lay 300-800 eggs in her lifetime over a couple weeks.
This is a good time to point out that these methods are geared towards the home gardener or homesteader with a moderate potato crop. To give you an idea of what we were able to successfully handle with no problem… we have around 160 potato plants this year.
Look for and Destroy Potato Bug Eggs
Once you’ve removed the adults potato beetles, the second step is to immediately go after the eggs. This is especially important in the beginning. Potato bug eggs can hatch in as little as 4-5 days, and we want to nip them in the bud!
I think that doing this made an incredible difference!
You will find the eggs on the underside of the potato leaves. I look for them by using my hand to gently push the potato plant over in each direction, exposing as much of the underside of the leaves as possible. The eggs are bright blaze orange against the green of the leaves, so they will easily catch your eye. Make sure to check all of the leaves, even the small ones and also the ones really close to the ground.
When you find a leaf with a cluster of eggs, pick that leaf off and throw it in your tin can. Every leaf you find with eggs is potentially saving you a lot of work down the road!
As long as I am still finding adult potato bugs, I still check for eggs. I had good success in checking for eggs every day for the first few days that the potato bugs showed up, and then every two or three days after that until I stopped finding adult potato bugs. It is more time consuming and harder work than just scouting for the adults, but its ultra-satisfying to find and eliminate a leaf with dozens of eggs on it!
Once I stopped seeing adults, I stopped looking for eggs. For me this was two or three weeks after the first adult potato beetles arrived.
How to Kill Potato Bug Larva
Inevitably you won’t catch all of the eggs, and some will hatch and turn into little potato plant munching machines. And these, these are the things that will actually destroy your plants- they’re small, but they’re voracious!
Don’t panic, it’s okay if this happens. It WILL happen.
Once they hatch, the larva will go through four different instars, which is the fancy name for developmental stages. They start off as itty bitty black and orange pin-head sized bugs, and turn into the most disgusting grub-like things. Oh how I hate grubs.
The itty bitties always seem to start out in the central area on the leaves they hatched from… which is kinda nice because they are all in one area. Every day they grow, they spread out a little bit more.
If you don’t catch them and they are allowed to get to their last developmental stage (in about 2-3 weeks) they will drop off the plant, burrow into the ground, and emerge as an adult potato beetle in 5-10 days to start the cycle all over again and fill your plants with eggs. Obviously we want to prevent this at all costs.
Organic Treatment for Potato Bugs
The bad news is that there aren’t a lot of organic and natural products that will kill adult potato beetles- they are notoriously hard to get rid of.
The good news is that the larva are much more susceptible to the organic products we have available, and we can definitely get rid of the bulk of their population.
This is the main reason why the combination of techniques- picking off the adults, scouting for eggs, and then treating the larva is the most effective solution.
So what are natural and organic products that kill potato bug larva?
The following section updated for 2019!
I’m starting with Diatomaceous Earth because it one of my favorite tools for controlling potato bug larva. This stuff works really well, especially for smaller larva, and it is incredibly easy to use- no mixing with water, no sprayers required, and you can use it safely any time of the day. The first time I used it I saw hash, potato soup, and french fries in my future.
What is it? The fossilized remains of a type of hard-shelled algae.
How does it work? By disrupting the exoskeleton, and causing the potato bug larva to dehydrate and die.
How do you use it? It’s a fine powder that is dusted directly onto the larva and leaves.
Other things to know about using Diatomaceous Earth:
It will kill many types of bugs, including good guys like lady bugs and bees. Bees are only interested in the flowers though, and potato bugs really aren’t, so the actual danger to bees is very minimal if you only dust the larva and leaves.
Diatomaceous Earth can be dangerous if inhaled. You don’t have to wear a mask or anything… just don’t snort it and be cautious if there are strong wind gusts.
It is only effective when dry. This means that you’ll have to wait to apply it after any dew dries, and you’ll need to be mindful of rain in the forecast- don’t apply it immediately before it rains or you’re just wasting your time.
It covers the leaves, preventing photosynthesis where you put it. Use Diatomaceous Earth– only where you see little potato bug larva. Do not use this preemptively or on plants that are not infested. The good news is that the wind and dew and rain will wash most of it off after a couple days. And the bugs will be dead at this time also, so that works out well for the plant’s sake.
In my experience, this killed the potato bug larva in less than a day and was quite effective. Sprinkle it on the bugs one day, and they have disappeared by the next! This will only work on the potato bug larva that get directly hit with it- sometimes they can be hiding under a leaf or in a place that the powder doesn’t reach, in which case they’ll escape death… this time.
Where do you buy Diatomaceous Earth?
Some farm stores will carry it, otherwise this brand is the best value I’ve found online. Just make sure you get one that is “food grade.”
For ease of use, I put the Diatomaceous earth into a standard-size used spice bottle for sprinkling- this worked wonderfully. Any larger vessel and I think it would have distributed too much at one time.
I also tried Neem Oil, and while it seemed to work okay, it wasn’t as convenient for me personally, although I know it is one of the top products that other people swear by for killing potato beetles.
What is it? Oil pressed from the fruits and seeds of the Neem tree.
How does it work? It disrupts things related to hormones like ability to eat and reproduce.
How do you use it? Spray on the leaves of the plant- the bugs need to eat it for it to work.
Other things to know about using Neem Oil:
The most important thing: get the right kind of Neem Oil and KNOW what you’re getting! I can’t stress this enough. The Neem oil you find in the gardening section of your hardware store is probably not the correct kind, unless you have a super awesome hardware store run by hippies.
Neem is too general of a term. When Neem is processed it turns into two main things: Azadirachtin and Clarified Hydrophobic Extract of Neem Oil (also sometimes referred to simply as “Neem Oil”).
Azadirachtin is what we want- it has the most bug-killing properties. Hydrophobic Extract of Neem Oil kills some bugs, but not as well and in the case of potato bug larva, possibly not at all. If you’ve tried Neem before and it hasn’t worked, it might be because you had the wrong kind.
So which Neem should you get and where can you find it? Get REAL, potent, potato bug-killing Neem Oil here.
There is a lot of information on the different mechanisms of how Neem Oil kills or deters bugs. Some report that it simply repels them, some say that it disrupts their hormones and causes them not to eat and they starve after a couple days, and some say it prevents them from reproducing. Whatever it is, it isn’t necessarily instantaneous.
It degrades quickly. Azadirachtin has a very short half life: 48 minutes to 4 hours in water, and around 2 days on a leaf’s surface. This is why the good stuff is sold as a concentrated oil that you mix yourself. If you plan to use Neem Oil, you will need to predict how much you’ll use, and make a new batch for every spraying session.
It can burn your plants if you mix it too strongly, or apply it in the middle of the day or in the hot, direct sun. Neem Oil is best applied early in the morning, or in the evening. And just make sure you follow the mixing instructions on the package. You’ll need a spray bottle for applying it too, by the way.
Where do you buy REAL Neem Oil?
You’ll probably have to pick this one up online, find the good stuff here.
As of 2018, Spinosad is my new favorite organic product for killing potato bug larva! We finally tried it, and wow was it a life-changer!
This is perfect for the situations in which you’ve missed a leaf with eggs, the eggs have hatched, and now there are hundreds of tiny larva all over the plant. One dousing with Spinosad and they are gone, often within hours! Miraculous!
This also works if you’re even farther down the line and the larva are quite large. I think that Spinosad works better on larger larva than then the Diatomaceous earth does.
What is it? A fermented substance produced by certain bacteria found in the soil
How does it work? It affects the nervous system of insects that eat or touch it.
How do you use it? As a spray on the leaves of the plant.
Other things to know about using Spinosad:
While it can be toxic to insects when they simply come in contact with it, the toxicity is low once it has dried. It is much more toxic to insects that eat it. It will be toxic to bees when wet and up to about 3 hours after first sprayed, so only spray when beneficial insects aren’t around, usually early in the morning or late evening. It is safest to use when the potato plants are not flowering.
Many of the popular Spinosad sprays available also come with a list of limitations broken down by fruit or vegetable type- things like the number of days between applications, how many times you can use it in one season, and how long you have to wait to harvest after spraying. Might want to read these if you end up using it a lot. Because of this, consider alternating it with one of the other products I’ve mentioned.
It is recommended to only mix as much as you will use in a single treatment.
There were no specific instructions for what time of day to use Spinosad, but since it is mixed with water you will want to avoid spraying in the heat of the day to avoid burning the leaves of your plants.
I believe that Spinosad is longer lasting and may be a good choice for someone who can’t dedicate a little bit of time every three days to potato bug duty. This would be my first choice if I walked into the potato patch and it was highly infested with tons of large larva (similar to potato devastation picture above). I wish I had known about this during the epic infestation of 2017- it probably would have save my potato harvest that year.
Where do you buy Spinosad?
There are several different brands that make this- you may find one at your local hardware store, or you can find it online here for a reasonable price.
My two best allies for potato bug control are Diatomaceous earth and Spinosad… and I find myself using them both throughout the season, depending on the situation that day. The Diatomaceous earth is fast, easy, and great if I only have a small amount of time, or am only available in the daytime. Spinosad is better for bigger infestations or larger larva, or if its a big job- like a lot of plants that have a lot of bugs. I’d recommend trying both and seeing what works for you!
Does Mulching Plants Prevent Potato Beetles?
In my opinion it does not. Multiple articles I read said to mulch all around your plants with a heavy layer of straw, so when the potato beetles crawl out of the ground they won’t be able to find the plants as easily, having a difficult time climbing through the straw. I’m calling BS on this one. If a potato bug can claw its way up and emerge through the dirt, and then walk a mile to find your plants, surely it can climb another couple inches through straw.
And while I do believe that mulching creates an environment that potato bug enemies might like and will help control them in this way, that’s leaving too much to chance for me.
Does Crop Rotation Prevent Potato Beetles?
It doesn’t hurt… and crop rotation is always a good idea for other reasons as well.
When potato bugs emerge in the spring, they travel on foot looking for potato plants and other members of the nightshade family. Reportedly, they can travel miles!
And here’s an anecdote for you. Remember I said that last year they decimated my potatoes, and I didn’t do anything to stop them, and presumably hundreds of them should have been overwintering in my garden? I planted six potato plants right next to this previous potato devastation area, and they are tall and beautiful and have not had one single potato bug on them! We have a second garden about 100 yards from this potato devastation area, where our main crop of potatoes is, which is where I’ve been treating for potato bugs this year. So… who knows.
Should I Dig a Trench? Should I Use Row Covers?
I almost took the plunge and got row covers in preparation for the potato bugs, and I’m so glad I didn’t. The techniques I outlined above, especially with using the Diatomaceous Earth have been very effective at keeping the potato bugs under control. Row covers can be expensive, you have to make sure you stake them down good, and I’ve heard stories that they don’t work all that well for this particular insect.
There is a technique where you dig trenches around your potato garden like a moat and line them with plastic. Supposedly when the potato bugs emerge from the ground and make their way towards the plants they fall into this trench and can’t crawl out. This sounds like a LOT of work, and also like leaving a lot to chance. And what if they emerge already in your potato garden? Then you did a lot of digging for nothing. And if it rains and they fill with water you’ll probably drown a lot of other bugs too, likely a lot of earth worms.
There are a few other similar potato bug control techniques floating around the internet, and in my opinion they are just too much work and not enough reward for the home gardener.
I’d love to hear what methods of potato beetle control have worked for you and also what area of the country you are in. Happy gardening!
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