Basic Insect Control In The Garden

There is absolutely no reason to have to resort to chemical insect controls in the modern garden. I ran an entire nursery organically so a small backyard garden is a walk in the park.
But yes, some insect damage is necessary.  Why? Because the vast majority of insects are trying to eat the bad guys.  If you want ladybug beetles, you need aphids. If you want butterflies, you need big caterpillars.

It’s a natural cycle. The only time I get serious about controlling insects in my flower or vegetable garden is when plant damage starts to rise above 10% of the leaf surface.
Anything less than that is cosmetic and no big deal.  Some gardeners let it get even higher.  And some control at 1% to wipe out all insects – the good and the bad. (but you won’t do this anymore will you?)

Tips for Insect Control

*Never use any pest control product without reading the label. I know, I know – you get the same advice from everybody but all you want to do is wipe out whatever’s eating your lettuce. Right. Me too.
But I’ve had folks write and ask why this fungicide wouldn’t kill whatever was eating the lettuce. And when I pointed out that it was an insect that was eating the lettuce not a fungus, they had problems understanding that just putting “something” on the plant wouldn’t fix it.
Or worse, they put things that were intended for non-food pests onto a food crop.
More than once, I’ve had to tell readers not to use a systemic poison such as Cygon 2E on a food crop. Yes, it would kill the insect but then you’d be eating the leaves that were poisoned with something that could really kill you. I note that accidents such as this have happened in our food chain in the past and people have become very ill.
I’ve also had folks ask why this product (such as insecticidal soap) turned their flowers pink or killed off an evergreen.

So know what you want to control and read the label to make sure you’re using the right product.  Everything you need to know – what the product works on and what it kills or damages is on the label.

Rules of thumb

  • Damage that happens at night and you can’t see any pest is often a slug. Look for slime trails on the tender leaves. Tomatoes eaten away in the middle from a small entrance hole is slug.
  • Black “soot” on leaves or fruit is often aphids. You should be able to see a small pear-shaped pest on tender growing tips.
  • Odd small holes here and there are often flea-beetles. These guys are really tough to see because they’re tiny and jump very quickly at the first sign of leaf movement (like you trying to see them).
  • Big holes on cabbage and broccoli crops are usually a green worm – the larvae of the cabbage butterfly.
  • Clouds of small white flying insects when you move leaves are whitefly.
  • Tomato plants that are disappearing before your eyes or overnight are (being eaten by) tomato hornworm. If you’re really quiet, you can hear the clicking of their eating. Squash them.
  • Squash leaves that disappear are normally squash bugs.


Again. Read the label because even organic products are not to be messed with.

Let me tell you a short story. In running my greenhouse, I switched to full organic controls and thought that soap sprays would solve my problems in the propagation house. While I had previously worn full spray suits with air packs to spray any kind of chemical, I assumed an “organic” spray wouldn’t hurt me. This shows you that I did this way too many years ago and that I was a bit naive at that time.
I loaded up the soap into my fog-sprayer. This is an electric sprayer that coats all surfaces with a fine mist of spray and uses high air pressure to get under the leaves and coat the entire plant surface. I had a great insect kill and was quite pleased with myself.
Until I got an almost instant “cold” and had trouble breathing – wheezing away like a mad scientist. The soap that I had been breathing worked quite nicely to strip away the protective layers in my lungs as well as those of the insects. It took me about a week to recover my full breathing and I never sprayed an organic product again without full protection.
Just because something is “organic” doesn’t mean it’s harmless. It simply means it degrades into the environment quickly and safely without dangerous residues. It doesn’t mean it won’t hurt you or your family.
Read the label.

A Good Collection of Organic Controls

There are a few organic controls that form the backbone for almost all the major pests.

Frost Fabric or Row Covers

They’re the same material but used for different purposes. It’s “gauzy” material that allows light and water to penetrate but not much else.
And what you do for pests such as cucumber beetles etc is to sow seed /plant your plants and then immediately cover the row quite loosely with this material. You need to give the plant lots of space to grow under there and easily push the fabric around so do not lay it tight to the ground by stretching it tightly. Eight to twelve inches on either side of the seed row is likely enough for most plants.
Bury the edges. Water and liquid feed.
Lift the row cover to harvest and immediately put it back down.
It also acts to hold in heat during the early spring and gives your plant a bit of protection from biting spring winds.
This is the simplest and easiest (read best) 🙂 way to control many tough vegetable garden pests.

Water Jet

The first is a jet of water from a hose. You’ll be amazed at how quickly a jet of water knocks aphids and other crawling insects off a plant. No fuss, no muss, no residue, no mixing, no spraying and no aphids left. When they’re knocked off the plant, they are helpless food for the larger beetles and other predators living at ground level.

Insecticidal soap.

This is a fast knockdown product for many soft-bodies insects you can see. Remember that you have to hit them with the soap to kill ‘em. If you can’t see them, you can’t hit them and can’t kill them. There is no residual power in the soap and once it is dry, it is pretty much done.
It has to be repeated regularly (read the label) and mixed properly so it won’t burn the plants. It does tend to do interesting things to the colour of some blooms so do check to make sure what it can be used on.


Another fast knockdown product. This can a lethal product for mammals as well as insects so do wear protective clothing when using it. It only has a life span of 24 hours in sunlight and degrades naturally and quickly in the soil. You don’t have to see the insects to kill them but it helps to understand what you’re trying to control because it won’t work on everything in the garden; please read the label on this before you use it.

Diatomaceous Earth

Great stuff for crawling insects that you can’t see. Registered for a wide variety of pests and able to work for long periods of time. This is very fine powder, the remnants of long-dead sea creatures. While the powder feels like talcum powder to us, to small insects it is composed of microscopically sharp shards. It would be like walking over broken glass to us. Insects are pierced by the shards and dehydrate. Safe for animals, pets and humans.


You’ll see it used in many countries for broad-spectrum insect control as well as a preventative for some diseases.

Iron Phosphate

This organic product is use in slug controls and is perfectly harmless to pets. Works like magic. Keep the beer to yourself from now on.
Those are the basics you’ll use for the majority of your organic insect controls. I include the Neem so you’ll understand the difference between the Canadian regulations and the advertising you’re likely seeing coming out of the U.S. This may change in the future but at the time of printing, this was the situation.

Bt (Bacillus thuringiensis)

is a bacteria that paralyzes the stomach of caterpillar-type pests. They eat the bacteria, essentially get a stomach ache, stop eating and crawl away and die. They do not die immediately but they pretty much stop eating fairly quickly. This product, while registered in Canada for some insects, can be difficult to find at garden shops. The bacteria is alive so it has a relatively short life span and while it is available for commercial use, there are no sources for consumers at the time of printing. You will see it mentioned in U.S. publications where it is available.

Got a Question About Organic Gardening Pest Control? More articles here! 

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