Back when I studied greenhouse tomato farming, I recall my instructor equating it to war against tomato pests. The gravity of his statement did not hit me until later when I tried farming tomatoes. The whitefly infestation in my greenhouse was so extensive you’d see a white cloud hovering over the tomatoes.

Tomato farming, while very profitable, is highly susceptible to pests and diseases. In this article, we will review common tomato pests in Kenya and how you can prevent them.


As the name suggests, whiteflies are small white insects that invade tomatoes to suck on the leaf sap. They prefer lying on the leaf’s underside and often migrate from one plant to another as they spread viral diseases. Spotting these white insects is easy if the infestation is high. Just shake the plant gently. You’ll know you have whiteflies if you see white insects fly out.

How to Control Whiteflies

  • Use Neem Oil – it repels pests and hinders them from feeding and laying eggs.
  • Use Beneficial bugs like ladybugs and lacewings – They will devour on the whiteflies, then migrate or die off once they are done.
  • Use insecticides like TataMIDA, Cyclone 505 EC, Radiant 120 SC offered by Osho Chemicals Industries Limited.
  • Amiran has a variety of insecticides that you can use to control a whitefly infestation.

Prevention Tips

  • Focus on spraying the underside of the tomato leaves.
  • If you choose to use insecticides, forgo using beneficial bugs. Insecticides might kill the bugs.


Generally known as Tuta absoluta, this destructive pest feeds on plants in the Solanaceae species, with its favourite host being tomatoes. Leafminers begin attacking a tomato plant from the moment they hatch, and they continue until adulthood.

A female leafminer lays approximately 260 eggs, and once they hatch, their larvae start mining into the leaf tissue. They gradually begin to desiccate the leaf, hence causing premature death. As the leafminers grow, they head to attack the fruit and stem. They are notorious for weakening tomato plants and reducing fruit yield. Leafminers can also indirectly damage the plant by permitting fungal diseases to enter through their feeding spots.

How to Control Leafminers

  • Place Sticky Traps – Sticky traps are ideal for detecting an infestation and monitoring it. The yellow or blue colour of the sticky traps attracts leafminers. When they come into contact with the sticky traps, they get caught on them.
  • Miglyphus – This beneficial parasitic wasp feeds on leafminers in all stages of growth.

Red Spider Mites

Red spider mites are small orange or red coloured mites that suck the leaf sap. They leave yellowish-white marks on the leaves, which eventually desiccate. Red spider mites prefer hot and dry conditions. They prefer hiding on the underside of tomato leaf where they can form webs and multiply. You will notice webbing on the plant’s branches or the leaf’s underside if the infestation is high. Red spider mites are not easily noticeable by the naked eye. Though with a magnifying glass, you can identify them.

How to Control Red Spider Mites

  • Use beneficial bugs like lacewings and ladybugs.
  • Use 2% horticultural oil.
  • Overhead irrigation – enables you to control the population.
  • Use Neem oil or insecticidal soap.


Example of tomato pests- aphids
An Aphid (Courtesy of Viktor Forgacs, Unsplash)

Aphids are tiny insects that suck sap, cause curling and yellowing of tomato leaves. They multiply quickly but are not difficult to control. If not managed, their population can hit thousands. Aphids can hide under a tomato leaf or on the flower and stem. As they grow, they shed off their skin and leave a whitish moulted skin on the leaves. Their dead skin can easily be mistaken for whiteflies.

How to Control Aphids

  • Use Horticultural oil, Neem oil, or insecticidal soap.
  • Spray mild soapy water.

Root-Knot Nematodes

Unlike other tomato pests that feed directly from the plant, root-knot tomatoes feed on the plant’s nutrients. They reside on the tomatoes’ roots, where they form bumps and hinder the uptake of nutrients.

Common signs for a root-knot nematode infestation are stunted growth and yellowing of plants. It easy to mistake these signs for water and nutrient deficiency. You can try pulling out a suspected plant to observe the roots. If you spot any bumps or galls, you have a root-knot nematode infestation.

How to Control Root-Knot Nematodes

  • Buy resistant tomato varieties.
  • Kill the nematodes with heat through soil solarization.
  • Practice crop rotation.


These horn-tailed caterpillars are large and easy to control through physical removal. They are, however, not easy to spot because their green colour blends with the tomato plant. They feed on the plant, then defoliate and leave dark green droppings. Their droppings are easy to spot. You should check for droppings or damaged leaves if you suspect hornworms have invaded your farm. Inspect it at least twice per week.

How to control Hornworms

  • Physical removal – remove the hornworms and dip them into soapy water.
  • Use beneficial bugs like paper wasps, lacewings and ladybugs.
  • Spray insecticidal soap.

Flea Beetles

Flea beetles commonly attack tomato seedlings. These black beetles love to feed at night, so you might fail to recognize them during the day. They leave small visible holes on the leaves after feeding.

The adult beetles feed on leaves, while their white larvae feed on the roots. For a small infestation, don’t be alarmed. Your tomatoes will outgrow the damage. A large one, however, might cause the seedlings to desiccate before growing to maturity.

How to Prevent Flea Beetles

  • Cover your tomato seedlings with a row cover – Row covers act like a net that keeps the flea beetles from reaching the seedlings.
  • Use Yellow Sticky traps.
  • Deploy beneficial nematodes – They will feed on the larvae at the roots.
  • Apply diatomaceous earth to dehydrate and kill the beetles.
  • Practice crop rotation with a crop that does not host flea beetles.
  • Spray insecticides like pyrethrin.

How to Prevent Tomato Pests in your Farm

  • Use tomato varieties that are tolerant to pests.
  • Weed out your tomato farm.
  • Inspect your farm regularly for tomato pests.
  • Avoid letting in many people on your farm, especially if it’s a greenhouse.
  • When you spot a pest on your farm, act immediately.

Closing Remarks

The best way to control tomato pests is by preventing them before they invade. Always be on the lookout. Don’t give up and don’t give in. A surplus payback awaits if you pass the hurdle of tomato pests and diseases. You can learn about tomato diseases and disorders here or how to identify and control tomato diseases here.

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Read: The Ultimate Guide to Tomato Farming in Kenya

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