Little Black Gnats On My Tomato Plants

Little Black Gnats On My Tomato Plants

Tomatoes are a popular crop in our gardens, and it’s also commercially grown. However, I consider tomato farming a bitter-sweet experience. Why? Despite being popular, tomatoes face several problems; indeed, pests are considered the worst. They lead to infections, and today, I look at little black gnats. What are the little black gnats on my tomato plants? 

Little Black Gnats are small insects that damage tomato plants severely. Using good soil, killing adult gnats, and using other biological methods such as spraying Steinernema Feltia kills black gnats. Also, mixing water with Nematodes and applying the solution as a soil drench kills black gnats.

Read further below to get information on how to eliminate all black gnats successfully and grow healthy tomatoes. 

Little Black Gnats On My Tomato Plants

The tiny black fruit fly-like gnats are small insects that look harmless but severely damage our tomato plants if not controlled. They’re either black or brown and about one-eighth of an inch. You find them in the potting area or the tomato leaves. 

The black gnats are first transported as eggs in the soil or are already on the ground. Also, since they’re tiny, they can get indoors through narrow openings in your greenhouse.

They lay eggs on damp soil and produce very fast, with an average female laying about 100 to 300 eggs. Eggs hatch into larvae that feed on new tender roots leading to delayed development of new roots and further wilting.

In less than two weeks of active feeding, they become adults, small like fruit flies. You find the adults on top of the soil and your tomato plant.

How Do I Get Rid Of Little Black Gnats On My Tomato Plants?

You eliminate the black bugs on your plant by maintaining ideal soil conditions, eliminating adult gnats, and using biological methods. The methods depend on your tomato plant location, whether outdoors, indoors in a greenhouse, or on your patio.

Getting rid of these gnats is not very hard, so relax because I have the solutions right here.

Maintain Perfect Soil Conditions and Practising Good Housekeeping for Plants

Avoid overwatering because bugs thrive in moist soils; let it drain well between watering. The best way to practice good housekeeping is to prevent the black bugs before planting your tomato plants.

Test the soil for bugs even before planting, as the first few weeks are the most crucial for your plants. Alternatively, clean your greenhouse before planting new tomato plants because weeds and other organic matter attract black bugs.

Not forgetting that these pests lay their eggs on moist soil, so always ensure it’s well drained. By this, the adult black bugs won’t lay eggs on dry soil as it doesn’t favor larva growth.

Also, add gravel or sand as mulch to your pot’s top inch of soil. Adding that mulch creates a dry environment where black bugs can’t thrive. However, ensure the plants have enough water daily to prevent hydrating that may kill them in drought conditions.

Eliminating Adult Black Bugs

Black bugs reproduce quickly; thus, their population increases fast. Despite that, you can eliminate them in several ways:

  1. Use of Yellow Coloured Sticky Cards

Use sticky yellow cards with adhesive on each side to capture them. Yellow is beautiful and highly visible; therefore, it lures them towards it. You place it on the soil surface, facing upright.

It also gives you an estimation of the black bug population in your tomato plant.

  1. Use of Apple Cider Vinegar Traps

Adding apple cider vinegar to a shallow water container is a simple and cheap solution for trapping adult black bugs.

You can also add some liquid dish soap. The smell of apple cider attracts the black bugs, and they get trapped in it.

  1. Use of Essential Oils

Spray strong essential oils like neem, thyme, peppermint, and rosemary on the leaves to deter the adult bugs. Note that you should use diluted oils only. You can use the manufacturer’s instructions to dilute.

  1. Use of Biological Methods

You can use the over-the-counter black bug sprays if all the other methods prove ineffective. They effectively eliminate adult black bugs as they contain pyrethrins that kill them. 

You can also use diatomaceous earth (DE), mineralized fossil dust that’s non-toxic. Mix it with the top layer of infested soil or in your pot before planting; it kills both larvae and adults.

What Are The Little Black Specks On My Tomato Plant?

The little black specks on my tomato plant are signs that my plants are affected by pests, diseases, or several issues.  These issues may come from overwatering, fungi, pests, nutrients, etc. The little spots affect the tomato plant leaves, fruits, and stems, which is a cause of concern.

Ensure you investigate the leading cause of black spots so that you can eradicate and prevent them from occurring again. Note that you can’t reverse the little black specs with any treatment; you can only limit the spread and treat the causes.

Below are some most common causes of black specs on the tomato plant.

Blossom End Rot

Blossom end rot is a disorder caused mainly by a calcium deficiency in the soil.  But if it occurs on a healthy tomato plant, it’s caused by the remaining soil being wet in the tomato growing season. 

It starts on the unripe fruit and looks like a small brown patch on the tomato underside where the blossom was attached initially. It doesn’t affect the leaves or branches either. 

Since it’s impossible to reverse the condition, once it affects your fruit, stop the spread by picking the affected fruits. Did I say you can consume the fruits? They are harmless; you can eat them by cutting the rotted part.

Do also note that the soil mostly has enough calcium, only that the plant cannot absorb enough. Therefore, you can increase the soil Ph by adding ash, lime, or chalk particles to the soil. 

If calcium is insufficient, spray the affected plant with the calcium spray and the surrounding plant.

Bacterial Speck

Bacterial speck is a tomato disease affecting leaves and fruits caused by a bacterial pathogen. It forms small, tiny needle pricks like black spots that appear in clusters.

The pathogens may result from infected seedlings or seeds, which mainly spread due to damp conditions.

You can solve this problem by spacing your plants apart (18-24 inches) to prevent the spread of disease. 

Septoria Leaf spot

It’s a disease brought by a fungus that lives on the soil and spreads through garden tools and human contact. It causes black spots underneath mature leaves. However, they change over time.

At first detection, the spots are light and dark brown with faint yellow around the edges and, over time, develop to black specks.

It’s caused by watering your tomato plants from the top rather than the base near the soil. The leaves, therefore, become too moist on the underside, allowing septoria fungus to thrive.

Tips to Control the Little Black Specs on Tomato Plants

If the black specs have excessively spread, uproot all the affected plants and dispose off of them. 

Here are tips to prevent the little black specs from appearing on your tomatoes again.

  • Ensure you plant a tomato variety that’s immune from certain diseases. Go for certified disease-resistant plants for different seasons of the year.
  • Test your soil before planting for any fungus and take measures, like adding calcium if required.
  • Space your plants well to have good air circulation to help leaves dry quickly. You should also prune and remove weeds when necessary.
  • Use mulching on your tomato plants like straw, plastic, or fabric mulch. It reduces splashing on the lower leaves, preventing disease transfer from the soil. However, avoid leaves and grass clipping from lawns treated with herbicides, as tomatoes are sensitive to many herbicides.
  • Use drip irrigation to avoid overwatering the soil and to ensure the foliage is dry. 
  • Practice good crop rotation to control pests and diseases. You can allow 2 years without planting tomatoes. Also, never plant seeds from affected fruits.
  • Control the black specks; remove any leaves with black spots early enough to slow the spread. 

How Do I Get Rid Of Gnats In My Potted Vegetables?

To eliminate gnats in your potted vegetables, eliminate the larvae stage using nematodes, sand top dressing, and avoid overwatering. I believe the goal of planting your potted plant is to have a good harvest of healthy vegetables. 

The only way to eliminate gnats is to stop them at every stage by killing the adult to avoid more eggs. And also eliminate the larvae.

First, use the yellow sticky traps to capture the adult gnats and use them early enough before they’re far gone.

Then top-dress the soil on your potted vegetable with sand grains. You block other insects from getting into the soil and prevent the adults from further laying eggs. In addition, adding a half inch of sand stops and traps the larvae in the soil. 

Nevertheless, the gnats may still wriggle and find their way to the top, and here is where you introduce nematodes.

Bring nematodes on top of your sand to destroy the larvae preventing the next generation of adult gnats. Ensure you conduct nematode soak for at least 2-4 weeks with a separation period of 3-7 days.


Will the Little Black gnats go away on their own?

The little black gnats can’t go away on their own; they continue to multiply and grow as the adults lay eggs. However, this doesn’t mean you can’t eliminate them from your plants. 

If you notice a new infestation of gnats, just let the soil of the affected area get dry. When dry, all the larvae will die.

On the other hand, with a grown infestation, you need more tough measures. Trap the adult gnats with the yellow sticky paper. Secondly, remove an inch of topsoil in a potted plant and add sand as mulch.

Then introduce nematodes to kill any emerging larvae.


It’s crucial to pick an approach that won’t harm my plants but will successfully eliminate the little black gnats on my tomato plants. However, getting rid of all the black gnats on your plants could be difficult.

But using the above-mentioned control techniques, you can be sure your plants will flourish until harvest time. They have worked for me and produced large harvests of the tastiest tomatoes.

Take note of the various strategies for gnat prevention and management online. Few of them, nonetheless, provide you with excellent outcomes. Act now to eradicate and prevent the infestation, and refrain from spraying pesticides on your plants.