Basil pests: leaves with black spots, worms, thrips…

Today we will see some tricks on how to grow basil in the garden and in pots. Specifically, we will see some of the most common basil pests that can appear when cultivating this aromatic plant.

Purple basil next to pepper plants to protect them from pests and enhance their flavor

Basil leaves are delicious in salads, and they also work well in dressings like pesto sauce. But in addition to its culinary uses, growing basil is interesting because this plant brings many benefits to the garden.

How to grow basil: planting, watering and other care

Growing basil next to the vegetables in the garden can be very beneficial because its strong smell keeps pests as harmful as mosquitoes or whiteflies away from the garden.

Due to its important role in the organic garden, we have already talked about this aromatic plant in other Agrohuerto posts, and I showed you how I started growing basil in pots. You can see it in the post How to Plant Basil in pots, where you will find:

  • Characteristics and requirements of basil.
  • Basil seedlings.
  • Transplant and containers suitable for growing in pots.
  • How to grow basil: watering and other care
  • Collection or harvest of basil.
  • Conservation and uses.

Today we will focus, more than on general care, on the fight against basil pests and diseases. Let’s see them!

basil pests

Below we will see which are the basil pests that most often affect this plant and what care is necessary for a sick basil plant to recover.

1. Star-shaped black dots and galleries on basil leaves: leaf miners

Leaf miners are typical basil pests. The larvae of the dipterans or flies lay their eggs inside the leaves and, when they hatch, the larvae dedicate themselves to making tunnels and galleries, feeding on what they find in their path.

Basil leaves with tunnels or galleries caused by leafminers

These galleries or tunnels in basil leaves are a common problem, and leafmining insects are usually to blame.

The best thing to do with a pest of basil miners is to eliminate it when it has not yet started to cause much damage, that is, before the new bug hatches from the egg. The most important thing is, therefore, to eliminate all the leaves that have these black spots with a star-shaped halo, and thus we will prevent the plague from spreading throughout the plant.

Black spots on plant leaves caused by leaf miners

In addition, this pest can be treated with an organic neem oil insecticide or with preparations containing the bacterium Bacillus Thuringiensis (which secretes toxins that kill the pest). More information about the leaf miners in the post about the liriomyza fly

2. Aphids, one of the basil pests

Aphids can come in many colors, but they are quite easy to recognize because of their oval shape and characteristic little legs. It is also one of the most common pests in the plants of the orchard and the garden…

Unfortunately, the strong smell of basil is often not enough to intimidate aphids, especially if the pest is already well established on other nearby plants…

Aphids on basil leaves

If you see these green and oval bugs on basil plants, try to get rid of them as soon as possible because they are insects that reproduce very, very quickly. Look how some bean plants from the HuertAula Cantarranas community garden that we visited were planted in just a few days.

Aphids bite the leaves to absorb and feed on plant sap. Yellow or brown spots appear at the points of the bites, causing the leaves to curl up and dry out, the deformation of the shoots… In addition, aphids can cause other problems: by sucking the sap they can transmit plant viruses, and the molasses they secrete attracts other pests such as ants and can cause the “bold” fungus to appear.

How to control basil aphid?

In the post « Aphids, how can we control them « we leave you the characteristics of this pest, how to recognize it and some ecological techniques to kill aphids.

In the “Pests and diseases” category you can also find several posts about ecological remedies or natural insecticides that can be done at home to fight against aphids and other basil pests.

3. Thrips on leaves

Thrips are very small, dark bugs that move fast. They are tiny and elongated, and they hide mainly on the underside of the leaves, in the folds, in the buds and in the flowers. They damage the leaves, leaving spots that are like a silvery to transparent film (what they haven’t eaten from the leaf…) which then dries.

thrips on a flower

They are located on the flowers, on the underside of the leaves and on the fruits and use their small mouthparts to scratch or scratch the plant surface, causing small silvery or translucent spots that later become necrotic, turning dark until they dry.

Treatment against thrips

One of the best ways to prevent thrips is to have sprinkler or micro-sprinkler irrigation, as thrips don’t like running water and won’t stay near plants that are irrigated like that.

In the post that Sandra wrote, Bugs in the flowers: flower thrips, you have more details about this pest and how to prevent and eliminate thrips in basil or in other plants in the garden.

4. Holes in basil leaves: snails and slugs

They are a relatively easy pest to eliminate because they are very easy to recognize and find both the damage they cause (large rounded holes, especially in vegetables and aromatic leaves, such as basil or lettuce) and the individuals themselves that are causing the damage. problem, which usually have a considerable size.

Holes in basil leaves caused by slugs

Their slow movement makes capturing them manually or with traps quite easy. He left you a post with tips on how to eliminate a plague of snails or slugs.

In addition to these insects, there are other pests that can attack this aromatic, such as beetles, green worms or jumping leafhoppers (cicadellids). Basil fungus or leaves with dry edges due to sunburn are also common problems that we will deal with in another post.

If you have photos of basil pests or have experience fighting any of these insects that we have seen in today’s post, do not hesitate to tell us in the comments thread below.


  1. Veitía, M., 2002. Record of the main pests in medicinal plants. Plant Health Research Institute Registry of the main pests in medicinal plants (INISAV)
  2. O’Farrill-Nieves, H. & Medina Gaud, S., 2007. Common garden pests, identification and integrated management. University of Puerto Rico, Agricultural Extension Service.
  3. Simon, J. & Peccoud, J., 2018. Rapid evolution of aphid pests in agricultural environments. Current Opinion in Insect Science, 26, 17–24.

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