yellow bugs on squash plants featured image

If you have a vegetable garden, I guess you’re very busy. And growing squash plants? The job doesn’t seem to be more accessible. When growing squash, encountering pests is often par for the course. One common but frustrating adversary is the minor, yellow bugs often found making a feast out of these plants. What are these yellow bugs on squash plants? And how to prevent/ treat them. Find out in this article!

These yellow bugs bite the fruits and leaves of the squash plants. It would be best if you were well-prepared to fight against these tiny insects. First, we need to know what they are.

Name These 3 Yellow Bugs Usually Found On Squash Plants

The three yellow bugs on your squash plants are yellow-body whiteflies, aphids, and cucumber beetles.

#1. Yellow-body Silverleaf Whiteflies

Silverleaf whiteflies are small insects with white or yellowish bodies (that’s why this type of bug also makes it to the list of white bugs on squash plants). They look like they are covered in a powdery silver or white substance. When you disturb them, they fly up in a cloud. You can find them on the undersides of leaves, especially when there are many of them.

This little insect has a yellow body, and you can find them on squash plants | Source: Wikipedia
Figure 1 from the document ENTFACT-319 | Source

Silverleaf whiteflies harm squash plants by feeding on their sap. This can cause stunted growth, yellowing and wilting leaves, reduced fruit production, and the transmission of plant viruses. To protect squash plants, monitor for whitefly presence and take preventive measures like reflective mulch and organic insecticidal sprays.

Reference: ENTFACT-319: Silverleaf Whitefly on Squash – Ric Bessin, Extension Specialist University of Kentucky College of Agriculture

#2. Aphids

Aphids, often called plant lice, are tiny bugs that can come in many colors, including yellow. They are round and soft-bodied and often appear in large colonies on the squash plant. Aphids also suck sap from the plant, causing leaves to turn yellow and curly. Another issue with aphids is the honeydew they excrete, which can grow sooty mold and attract other pests.

aphids on summer squash flowers
aphids on squash foliages
Credit: Janine Spies, University of Florida


#3. Cucumber Beetles

Cucumber beetles have different colors: striped ones have a yellow body with black stripes, while spotted ones have a yellow body with black spots. These beetles can cause damage to squash plants and other cucurbits, especially immature plants. Beetles are around throughout the growing season and eat various plant parts, such as flowers and fruit.

Spotted cucumber beetle adult | Credit: J.P. Michaud, Kansas State University, – Source
Striped cucumber beetle | Credit: Clemson University – USDA Cooperative Extension Slide Series, – Source

They feed on leaves, stems, and flowers, causing harm and spreading diseases like bacterial wilt. To control cucumber beetles, use row covers, rotate crops, attract beneficial insects, handpick them, or use organic insecticides as a last resort. Monitoring and taking action can protect your squash plants and promote a healthy harvest.

Reference: CUCUMBER, SQUASH, MELON & OTHER CUCURBIT INSECT PESTS – Factsheet | HGIC 2207 – Clemson University HGIC Cooperative Extension

Ways To Handle These Yellow Bugs On Squash Plants

Method 1: Catching Them By Hand

Guess what? Your hands can be one of your best tools in the fight against pesky garden bugs. Seriously! If your garden is small enough, why not give it a go? Catching squash bugs by hand is safe and effective but requires time and patience. Just pick ’em up and drop them into a soapy water bath – this will get rid of them for good. The best time to do this is in the morning or evening when they’re most active.

Remember to check the leaves’ undersides, especially near the soil. That’s where these bugs like to hide. Also, watch for tiny yellow eggs on the underside of the leaves. If you find any, gently brush them into your soapy water, or use sticky tape to remove them.

It’s essential to keep this up every day. Trust me. It’s a battle you’ll want to stay on top of. Even missing a few days can give these bugs a chance to harm your precious squash plants.

I will not ignore the elephant in the room here. This method is time-consuming. There are other options. Try giving your plants a good spray with a water hose. Some folks even swear by using hot water in the late afternoon. Row covers in early spring are also a great option. Or else, try other methods after this one.

Method 2: Using Repellent Plants

This method is the usage of repellent plants. You grow them along with your squashes. They will take control of the bugs. Two companion plants are nasturtiums and white icicle radishes.

How to grow them? You had better grow companion plants between the squash beds for the highest efficiency. Other choices are oregano, marigold, calendula, and dill. They can also protect your plants and keep squash bugs away from your garden.

Method 3: Using Beneficial Insects

How about taking advantage of tiny animals in the garden to stop harmful insects? Not all insects are dangerous for squash plants. Some are good, while some are bad. It’s a good idea to kill squash bugs using beneficial insects. You can cut down the pesticide of chemicals.

Insecticides can eradicate both beneficial insects and squash bugs. The method is like a knife with two blades. It’s great if you can use insects as a weapon to eliminate bugs. A few beneficial insects are Tachinid flies or Trichopoda pennipes. They can stop the growth of squash bugs.

Tachinid fly on a leaf
Tachinid flies on a leaf.
trichopoda pennipes
Trichopoda pennipes. Credit:

Beneficial insects will lay their eggs on the adult squash bugs. Eggs will hatch and eat the host. Adult squash bugs will be the food of young beneficial insects. This’s how beneficial insects remove squash bugs.

What is more?: If you grow dill or calendula and squash plants, Tachinid flies will be attracted by their pollen and nectar-rich flowers.

Method 4: The Diatomaceous Earth Powder

Diatomaceous Earth powder

Diatomaceous Earth powder is made from ground-up diatoms. It creates microscopic cuts in the exoskeleton of insects and makes them dry out. Two types of Diatomaceous Earth powder consist of food grade and industrial grade. The food grade is to solve the problems with your garden and pest. Sprinkle diatomaceous earth on the ground right under the plant. Diatomaceous Earth powder cannot take effect when it’s wet. Therefore, you need to sprinkle a new layer of powder after the previous layer gets wet.

Adult squash bugs are not injured due to Diatomaceous Earth powder because they have a hard shell; however, squash bug nymphs still are killed. The nymphs don’t have such a hard shell, so they are vulnerable.

Don’t let the powder leave on the blossoms. It may harm beneficial insects like bees, ladybugs, or Tachinid flies. Only use it in certain areas.

Check this article: Cucumber Plants Dying From Bottom Up – How To Revitalize Your Garden.

Method 5: Checking Your Mulch

Why do you need to check the mulch? Many people often sprinkle a layer of mulch around plants. Do you know that it is like a protective cover for squash bugs? They like to hide under the mulch layer. Mulch will attract bugs, which isn’t suitable for your garden.

The solution is another cover, like a plastic sheet. You can remove mulch and choose another material to cover the base of the plant.

Method 6: Using Sacrificial Plants

This method is quite good. You can make use of other plants to support your squash plants. For example, we try to plant three yellow scalloped squashes along with one green zucchini. We find that squash bugs attract yellow scalloped squash more than green zucchini. They are often the first to be swarmed and fall.

Therefore, we consider yellow scalloped squash as a sacrificial plant. You can also grow one plant type but increase the number of plants. Plants of the same type can become sacrificial plants. However, it’s like a bet. You suffer massive damage if squash bugs destroy all plants in the garden. It would be best to try many types of plants that squash bugs don’t prefer, like butternut squash.

It’s necessary to understand the weather conditions, climate, and life cycles of insects. You will apply methods effectively. Many gardeners can start growing squash plants later but still succeed and even stop the squash bugs’ attack. It would help if you tried to plant one or two months before the bugs worsen. Planting in the spring, early summer, or late summer is better for preventing bugs.


And there you have it, green thumbs! Armed with these tips, you’re ready to wage war on those pesky yellow bugs tormenting your squash plants. Remember, it’s all about vigilance and consistency. Check your plants daily, act quickly at the first sign of trouble, and don’t shy away from using various methods to keep these pests at bay. Your garden is your sanctuary, and you have what it takes to protect it. So go forth, keep those yellow bugs in check, and here’s to a bountiful, bug-free squash harvest!

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