Skip to Content

How to Identify and Get Rid of Watermelon Pests

After weeks of working hard in your garden, you discover your watermelon plants aren’t doing so well. Instead of looking forward to slicing open your homegrown melons, you’re searching for how to save your plants. It’s discouraging when there are so many things that could be wrong. 

Don’t worry. I’ve listed how to identify and treat the nine most common watermelon pests. Keep reading to learn more!

1. Aphids

Watermelon pests, aphids

How to Spot Aphids

If you notice the leaves withering on your watermelon plant, there’s a chance you could have a particular set of watermelon pests…a melon aphid infestation. Aphids are tiny insects that range in color from pale green to black, depending on weather conditions. 

These watermelon pests hang out on the underside of leaves, where they feed on the plant’s sap. Not only do they steal the watermelon plant’s nutrients, but they also secrete a sticky substance that exposes the plant to a high risk of sooty mold. 

How to Get Rid of Aphids

Sometimes nature takes care of itself. If you have lady beetles present, they will usually control any aphid populations naturally. 

There are also some preventative measures that you can take to keep aphids from destroying your plants. Using row covers or reflective plastic mulch will deter aphids from visiting your garden. For already existing infestations, apply horticultural oil to your plants according to the application instructions. 

2. Cucumber Beetles

Cucumber beetle

How to Spot Cucumber Beetles

Cucumber beetles are some of the most damaging watermelon pests you can have. They are about a half-inch long with three black stripes running down their yellow wings. The beetles will lay eggs in the soil, and once they hatch, they’ll feed on the roots, stems, and foliage of watermelon plants. 

Once the beetles have fed on the foliage, they will usually move to flowers or fruit. Even though the damage caused by feeding is only cosmetic, these watermelon pests can also carry bacterial wilt, which will kill your plant once infected. 

How to Get Rid of Cucumber Beetles

There are several things you can do in your garden to prevent cucumber beetles. Use row covers, and always clean up leaf litter at the end of the season. You can also mulch around your plant to deter the beetles from laying eggs in the soil. 

If you already have cucumber beetles on your plants, try applying neem oil to the foliage to get rid of the beetles. 

3. Leafminers


How to Spot Leafminers

Leafminers are small white flies that lay eggs on top of the leaves by piercing through them. As the larvae grow, it causes more damage to the plant’s foliage by creating mines, which are squiggly lines throughout the foliage. This can be detrimental to seedlings.

As adults, these watermelon pests feed on the plant’s flowers. 

How to Get Rid of Leafminers

Luckily, leafminers have several natural enemies that will take of them without you having to do anything. It’s also important to note that pesticides should be used sparingly, as they can kill off the natural enemies of leafminers. Try using neem oil instead. 

Make sure to also clear any weeds that surround your watermelon plants, which provide great hang-out spots for leafminers. 

4. Armyworms


How to Spot Armyworms

Armyworms are caterpillar-like watermelon pests that can infest a garden by the dozens (or even hundreds.) There are several types of armyworms, but the kind you are most likely to see in the U.S. have a tan body with yellow stripes. During the daytime, you may not spot them, as they tend to hide on the underside of foliage. 

If you do happen to spot an armyworm after noticing damage to your foliage, it’s important to take action as soon as possible to save your garden. 

How to Get Rid of Armyworms

If you’ve ever had to deal with Japanese beetles, the process of removing armyworms is quite similar. You will need to remove the armyworms by hand and place them into a bucket of soapy water, where they need to stay for about an hour. 

Once you’ve removed all the armyworms you can find, apply neem oil or Spinosad to your garden to prevent any further infestations. 

Did you know that birds are natural enemies of armyworms? It’s not a bad idea to move your birdhouse near the garden to help curb any armyworm infestations. 

5. Spider Mites

How to Spot Spider Mites

If the leaves on your watermelon plants are yellowing with tan undersides, there’s a good chance you’re looking at spider mites. Similar to aphids, these minuscule watermelon pests feed on the underside of leaves by sucking the sap out of the plant cells. Affected leaves can die, exposing your watermelons to excessive sun. 

Because spider mites are so small, a good trick to spot them is by holding a white piece of paper under a leaf. Tap the leaf and see if anything falls onto the paper. 

How to Get Rid of Spider Mites

There are several beneficial insects that feed on spider mites, so it’s important to try and take care of pests naturally. If you see that your spider mite problem is not going away, apply neem oil to your plants to get rid of these watermelon pests. 

6. Cutworms


How to Spot Cutworms

Cutworms are caterpillar-like watermelon pests that live in the soil of your garden. At night, they come out to feed on the plant’s stem until they are satisfied. Most watermelon plants aren’t able to survive the damage that cutworms inflict and will usually fall over and die. 

If you suspect cutworms, dig in the soil surrounding your plant to look for any presence of them. 

How to Get Rid of Cutworms

A good preventative measure is to wrap cardboard around the plant stem to protect it from damage. If that doesn’t seem to help, visit your garden at nighttime to see if you can spot the cutworms. Insecticides can also be used to help with cutworm populations. 

7. Red Pumpkin Beetles

Red pumpkin beetle

How to Spot Red Pumpkin Beetles

When you hear the name red pumpkin beetle, you probably don’t assume it’s a pest that would affect watermelons. Unfortunately, red pumpkin beetles can pose a threat to your watermelon plants, especially at the seedling stage. They are red in appearance with small oval bodies no larger than eight millimeters. 

The red pumpkin beetles feed on the foliage of seedlings early in the season, leaving only the veins of the leaves attached. The damage caused by these watermelon pests often causes the seedlings to die before they get established. 

How to Get Rid of Red Pumpkin Beetles

Controlling red pumpkin beetles is all about taking preventative measures. If you’ve had an infestation in the past, plant this year’s watermelon and squash plants on the other side of the garden. 

It’s important that your watermelon plants make it through the seedling stage, as the beetles don’t affect mature plants nearly as much. Pay special attention to your seedlings, fertilizing and watering them, to encourage fast growth. You can also apply neem oil to help control these watermelon pests. 

8. Thrips


How to Spot Thrips

Melon thrips are so small that you’d never know they were there by just looking at your plant. But, these watermelon pests can still cause some large damage. The thrips hide in young stems and flowers, feeding on the plant throughout the entire season. 

The leaves will start to turn yellow, then wither and fall off the plant. As your plant loses leaves, the developing fruit can be exposed to too much sun, allowing the watermelon to get sunscald. 

How to Ged Rid of Thrips

Beneficial insects, such as lady beetles, can naturally take care of thrip populations. You can also use row covers to help protect your watermelon plants. 

For heavy infestations, regularly apply an insecticide. Make sure to rotate the insecticide you use every other week, as the thrips can build up resistance to one type. 

9. Cabbage Loopers

Cabbage loopers

How to Spot Cabbage Loopers

Cabbage loopers are caterpillars that feed on the foliage of watermelon plants. To move, the cabbage looper arches its back, bringing its front legs to its back legs, which creates a loop (hence the name!). 

These watermelon pests will create a cocoon under the leaves as they begin to mature. Adult cabbage loopers turn into brown moths, which will lay their eggs on both sides of the leaves. The cycle can repeat several times per year!

How to Get Rid of Cabbage Loopers

Visit your garden often to inspect for cabbage loopers. Once you’ve spotted them, pick them off the plant and drop them into soapy water for about an hour. You can also apply neem oil or Spinosad while the caterpillars are young. 

Wrapping Up Watermelon Pests

Don’t let watermelon pests ruin your harvest. By taking the preventative measures above, you can still have delicious watermelon this summer, or at least know what to do next year!

Want to learn more about this iconic summer fruit? Then visit our watermelon plants page to learn more about watermelon planting, growing, cooking, and more!