How to Control Squash Bugs (Soapy Water Method)

Female squash bug laying eggs on a Zucchini squash leaf.

    To understand how to control squash bugs, you first need to understand the life cycle of this prolific pest. Like any other garden pest, there are already tons of videos out there explaining how to control them—but I want to dig into the science behind the method I use and why it works.

    Before I explain the soapy water method, let’s talk about squash bug behavior and their life cycle. If you want to conquer your enemy, you need to understand your enemy- right?

The Life Cycle of Squash Bugs

    In spring, squash bugs take flight in search of a host plant. This is why crop rotation doesn’t work with them; they’ll just fly to your garden anyway. Squash bugs will come from over a mile away, so they can travel long distances.

Squash leaf that is heavily infested with different ages of squash bug nymphs. You can see the extensive damage that feeding has caused; the dead (browned) sections of the leaf are areas that have been fed on frequently. The rest of the leaf would have collapsed rapidly. 

    Once they find a host, they begin feeding and laying eggs. Within 5 to 10 days, those eggs hatch. The young nymphs usually stay on the underside of the leaves. They don’t move much because they’re so fragile, even when it's quite hot outside or it begins raining.

    Older nymphs and adults, on the other hand, are sneaky. They hide during the hottest part of the day, when storms roll in, and even at night. This means that while you might not see them during your daily garden walk, they’re there.

    Nymphs mature in 4 to 6 weeks, at which point they begin laying eggs themselves. That’s when populations explode seemingly overnight; suddenly you’ve got multiple generations all hatching and laying at once.

    Here’s the good news: while they’re impossible to completely eliminate (because new adults keep flying in all summer), population control is absolutely possible. It takes 5 to 8 weeks for a squash bug to go from an egg to maturity, which gives you a good window of time to act.

    Personally, I don’t even bother picking eggs off leaves. It’s easier and less frustrating to spray the newly hatched nymphs with soapy water; however, others find it easier to remove eggs from the leaves.

Female squash bug laying eggs on top of a squash leaf. You can see the color change in the eggs; the older eggs have turned a golden color after being exposed to air, while the one she just laid is white. A female will lay several clutches in her lifetime. 

How Squash Bugs Breathe

    Here’s where things get interesting. Squash bugs breathe through tiny tubes on their bodies that act like lungs. Normally, water beads up and rolls off of their bodies, so they stay safe in the rain.

    Even if they fall into a puddle, air bubbles form around their bodies and these tiny tubes, allowing them to continue respirating instead of drowning. That bubbles actually pull oxygen out of the water too, so the bug won’t suffocate; it can hang out until it finds dry land again.

    This survival mechanism is why a simple cup of water won’t kill them, nor will a swim in a puddle.

Older squash bug nymphs that are close to maturity, sheltering in a rotting squash leaf that likely died due to being fed on by these squash bugs. 

Why Soapy Water Works

    Soap changes everything. It breaks the surface tension of water. When you spray a squash bug with soapy water, the liquid infiltrates those little breathing tubes. Without surface tension to protect them, they can’t form an air bubble. The tubes fill with water, and the bug essentially drowns.

But here’s the catch:

• You must spray and saturate the bug directly; spraying leaves alone won’t work.

• It won’t affect the eggs, only nymphs and adults.

• You’ll need to keep monitoring and spraying as populations grow.

    I use egg clutches as my indicator. If I see just a few clutches on my plants, I leave them. But if nearly every leaf has clusters or if there are multiple clusters on one leaf, that’s my cue to spray. I’ll spray the squash bugs with soapy water, then repeat about 5–7 days later after most eggs have hatched.

    For new gardeners, weekly spraying is a good habit until you get a feel for the tipping point in your own garden.

    If you want to save time with spraying, you can also keep your plants covered so that the females cannot physically reach them in order to feed and lay eggs. Below, you can see that I netted my plants to keep harmful bugs out (primarily the squash vine borer, a particularly nasty pest.)

These squash plants are covered, netted so that squash vine borers and squash bugs cannot get to them. This prevents females from laying eggs, halting squash bug damage and vine borer damage until later in the season.

When to Spray

    Timing matters! Spray during active feeding times, usually in the morning or evening when it’s cooler and pollinators aren’t as active.

    If you spray in the morning, rinse your plants afterward so pollinators aren’t exposed to soap residue. You may have terrible squash production if you spray while pollinators are active, so try to avoid spraying while pollinators are buzzing about.

    Avoid spraying during the heat of the day, because wet leaves under harsh sun can burn. You also won't find many squash bugs out and about, so this isn't an effective time to spray. 

    I personally prefer evening spraying, since my plants are already used to evening showers from summer storms.

Small bee pollinating a squash blossom after the rain.

My Simple Method

Here’s exactly what I do:

1. Mix water with just a little bit of soap in a spray bottle. You only need enough soap to break surface tension, don’t overdo it. Dish soap or Castille soap will work. 

2. Spray the underside of leaves, stems, fruit, flowers, and especially the base of the plant.

3. Start at the bottom and work your way up! Squash bugs will run when you start spraying, and you don't want them running towards cover until you've already saturated them.

    It usually takes me about 10 minutes to spray all of my plants. It’s cheaper, easier, and less toxic than pesticides, and you can even spray right before harvest without worrying.

    For vine borers, I’ll do injections as usual, then I like to follow up with my soapy water spray so everything’s done at once.

Young squash bug nymph on a squash leaf that's been heavily damaged by squash bugs. 

Final Thoughts

    Squash bugs can feel overwhelming, but with the soapy water method, they’re actually one of the easier pests to manage. It’s cheap, quick, and effective.

    I hope this helps answer your questions about squash bugs! If I missed something or if you’ve got your own tips, drop them in the comments; I’d love to hear how things are going in your garden this season!

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How to Eliminate Squash Bugs Using the Soapy Water Method

Control and get rid of squash bugs with soapy water!