What’s Eating My Basil?: 5 Causes of Holes in Basil Leaves

Basil is popular in the garden and wonderful to cook with. It makes an excellent companion for your tomato plants, and pollinators adore the nectar from its sweetly fragrant flowers. Attractive, aromatic foliage and tons of flavor make this an all-time favorite, so it’s no surprise that insects also like to snack on this tasty herb.

Whether it’s surprising, it’s certainly still disappointing to find your pretty basil plants with chewed-up leaves. Holy basil is nice, but holey basil is not. Any time we notice that something is munching holes in our plants, it’s a cause for concern. When it’s a plant you intended to eat, it’s even worse. 

Many insects are fond of basil, but they don’t all leave holes. If you’re specifically dealing with the issue of holes in your basil leaves, there are a handful of potential culprits. Let’s talk about which of these pests could be leaving those leaves looking lacy and chewed on. 

The Long Answer

If you woke up to holes in your basil leaves today, you’re probably looking for answers on who or what caused the damage and how to stop it from worsening. There are several possibilities and different methods of stopping the issue from getting worse. If you can identify the culprit, it’s much easier to stop it from continuing to destroy your herbs.

Grasshoppers

Grasshoppers are one of the pests that may be leaving holes in your basil leaves. The holes left behind by these jumping insects usually have jagged edges and may be the result of a large group of babies. You may even catch them in the act.

How to Fix It

Creating a balanced ecosystem is key to keeping any infestation under control, and grasshoppers are no exception. If you keep a healthy garden with plenty of diversity, you should have a decent number of adult grasshopper predators. Ladybugs and their larvae, mantids, birds, and wasps all like to feed on grasshopper nymphs and eggs. 

Neem oil is a safe alternative to chemical pesticides for treating all of your plants, and especially the edible ones. It will help to eliminate the existing hoppers and ward off more in the near future. A spray made from garlic and chili peppers is also a good deterrent for these pests. Remember to reapply after rain.

Using trap crops is an effective way to keep grasshoppers off your basil. Trap crops are plants that grasshoppers prefer to feed on. Nasturtiums and sunflowers are great companions that will draw grasshoppers away from your basil. 

Slugs

Slugs are a common pest that eats holes in basil plants. They leave jagged and irregular holes, and there are lots of them. Slugs are especially attracted to young, tender basil plants. This is more serious as the smaller plants are more vulnerable, and slugs will take them down much faster. 

Some of the elements that make your basil more vulnerable to slugs include planting it in moist, shaded spots and using mulch. Mulch gives them a spot to hide, and these mucus-covered gastropod molluscs love cool, moist spaces. 

How to Fix It

Barrier methods are typically a safe and effective way to keep slugs off your basil. Slugs dislike caffeine, and the smell and texture of coffee grounds repel them. Diatomaceous earth and crushed eggshells sprinkled around your plants are another deterrent. Both have sharp edges that slugs will avoid. 

It’s easy to trap slugs using beer or grapefruit traps. Slugs also have many natural predators. An active and balanced ecosystem will bring these predators to the garden. Birds, beetles, frogs, and toads all like to make a meal out of soft and tasty slugs. 

Keep the space around your basil plants free of debris for them to hide in. If you see them, you can pick them off by hand and drop them into a bucket of soapy water. 

Caterpillars

Several types of caterpillars may be eating holes in your basil leaves. Loopers, armyworms, grubs, and the larvae of owlet moths are all potential offenders. You’re likely to catch these in action as they eat slowly and will hang around until they eat their fill. 

How to Fix It

As with grasshoppers, garlic spray is a good deterrent for most caterpillars. They have a number of natural predators, so attracting them is a great way to keep numbers and damage to a minimum. Plant nectar plants nearby to draw parasitic wasps. Birds and spiders also prey on caterpillars. 

A solution of soap and water can help get rid of or kill caterpillars that eat your basil plants. At the very least, it will wash them away, and hopefully, keep them away. Bacillus thuringiensis is a natural bacterium that is not harmful to humans, but will kill caterpillars effectively. 

Katydids

Katydids are similar to grasshoppers, and they like to eat basil leaves. The young nymphs usually feed from the middle of the leaves, while adults often munch around the edges. Some types won’t cause much trouble, while others can be quite aggressive and damaging. 

How to Fix It

If you see them during the day, they are less active, and you can often pick them off by hand. If you want them gone, drop them into a bowl of soapy water. They tend to be slower when the weather is cool, so mornings are usually the best time to catch them. 

If you can’t get rid of them with manual control methods, neem oil or insecticidal soaps are effective against katydids. Try to use these products in the late afternoon when pollinators are not present. Never use them on plants while in bloom. 

Japanese Beetles

I find Japanese beetles to be quite pretty. However, they can also be highly destructive and are fond of basil plants. Japanese beetles are a type of scarab beetle, and they are not native, so they don’t have as many natural predators here. 

The larvae mostly feed on the roots of grasses, but the adults can do significant damage to your plants, including basil. Their damage is distinctive in that they defoliate the leaves. They eat all the tender leaf material but leave the veins. This is also called skeletonizing.