How to control squash bugs in the garden

I don't normally have a problem with squash bugs. I grow zucchini every single year and can't recall ever seeing more than a couple of squash bugs here and there, over the years. Occasionally I'll have a wilted leaf and I'll check and if I see any eggs I'll squish, remove or otherwise kill them. That's always been enough to keep squash bugs at bay.

Till this year.

It started a few weeks ago when I went to pick a zucchini from the garden around dusk. There were squash bugs of various ages on it. I had never seen that many before but I very carefully picked the zucchini then submerged it into a bucket of water that was sitting nearby, washing off the bugs and leaving them to drown.

I checked for eggs the next day but didn't see very many and removed the ones I did see. I then promptly forgot about it till a few days ago when I once again went to get a zucchini in the evening. This time it was already dark out and I took a flashlight and the zucchini I wanted to pick was covered with squash bugs!

Controlling squash bugs

I grabbed the diatomaceous earth and dusted the area then figured I'd wait till morning. The next day I took a very close look at all my zucchini plants and there were several egg clusters and and even a small group of insects that had recently hatched! See photo below, click to enlarge it.

Find and remove squash bug eggs

The first thing you'll want to do is to remove any eggs before they can hatch! The eggs are fairly easy to spot. The adult squash bug lays the eggs in a cluster, usually on the underside of a plant leaf. They are small, oval eggs that are a bronze or copper color. 

Just flip up the plant leaf and look for the eggs near the leaf rib. They can lay the eggs anywhere, it's just most likely to be in the more protected area where the ridges meet under a leaf.

Removing the eggs keeps new insects from hatching but it's important to kill the ones that are already hatched. They overwinter in garden debris under leaves inside mulch etc. So I needed to remove/destroy as many eggs as possible now, plus destroy the already hatched squash bugs so they don't make it to winter.

Either smash the eggs, scrape them into a bucket of water, throw them into the garbage or pull the leaf off and burn it. I don't recommend pulling a leaf off for a tiny section of eggs, but if your infestation is bad enough....

Signs of squash bugs on plants

Inhindsight I should have known to look for squash bugs being that my zucchini plants had a few leaves that were wilted and damaged. Zucchini leaves will wilt, dry up, then turn black and brittle when suffering with a squash bug problem.

This is because as the bug bites into the leaf to suck out the moisture, it injects a toxin which then kills off the leaves.

Squash bug damage on tomatoes

Everyone talks about how much trouble squash bugs create on a zucchini vine, but no one mentions that they also go after tomatoes! After I dusted the zucchini and other squash plants I started to notice my tomatoes were blotchy. I also noticed some squash bugs on the tomato plants but I didn't realize the two were related!

When squash bugs feed off the vines and stems of the tomato plant the plant will often die from that point on. So you'll have a tomato plant with a random dying branch. Same as zucchini plant leaves.

When squash bugs feed off the actual fruit, you'll get the result in the picture above. The larger yellow blotches are caused by them feeding on the green fruit and the tiny blotches are caused by the squash bugs feeding off the mature fruit after it has started to ripen.

That's basically that toxin we talked about earlier spreading under the skin of the tomato...so, don't eat those!

How to get rid of squash bugs

Your main steps to getting rid of squash bugs:

• Pick off and destroy eggs
• Remove and destroy squash bugs
• Remove damaged leaves. Burn or put in garbage, do not compost.
• Treat plants with neem oil to discourage adult squash bugs from laying eggs on them.
• Remove mulch from close to the plants.

How to catch and kill squash bugs

As mentioned earlier, they are pretty active in the evenings so if you're trying to kill the bugs you'll have better luck then. They are usually just hanging out on the leaves and fruit of the plants. If there are some dead leaves, bugs and their eggs can both be found on these leaves.

Two of the most effective tools in my organic arsenal are diatomaceous earth and neem oil. If you're not worried about using organic insecticides, then Sevin dust works very well too. 

Sevin actually works better on the adult bugs than the DE does. If you want to keep your garden organic though, you can hand pick the bugs and drop them in a bucket of water with a few drops of neem oil.

Dust the bugs, eggs and the leaf of the plant. Cut off any dying leaves. Put these in the garbage or burn them immediately. Do not compost them!

Related reading: How to get rid of stink bugs indoors!

How mulch hides squash bugs

This was the first year I've had an infestation quite this bad and this is also the first year that I used straw mulch throughout my entire garden. Coincidence? Unfortunately, no. 

Squash bugs like to hang out under the mulch where it's cool. They use it to hide in and unfortunately for me, it works well for them! Don't mulch all the way up to the base of the plant. I pulled back the mulch to expose the bare ground and it helped me get the infestation under control!

I also dusted some diatomaceous earth at the bottom of the plants to keep the bugs away. Don't dust the flowers as you don't want to kill off any beneficial pollinating insects! 

Preventing squash bugs

The squash bug only has 1 life cycle a year. The adult squash bugs overwinter in garden debris and emerge in spring to mate and the female starts laying her eggs. These eggs will hatch shortly and the nymphs will grow into adult insects. 

Since the female lays eggs all season long, not all the nymphs will have grown enough to survive the winter. These will die off, but the ones that have become full grown can survive winter. To get rid of these bugs you'll want to remove all garden debris. I usually pull it out and burn it after the first frost.

You don't have to burn your garden debris. However it is a good practice after dealing with an insect infestation. Crop rotation is another good practice to help prevent repeated infestations. 

Companion planting is also very useful as nasturtiums and other flowers are known to repel squash bugs. Unfortunately this year I didn't plant marigolds in my garden, and I battled the biggest squash bug infestation ever! *sigh*


Hopefully you won't have to deal with squash bugs this year, but if you do...these steps will help you to get them under control quickly!


Want to learn more about growing your own food? Click here for my other posts on growing your own food, herbs and flowers.

~L

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