Effective Ways to Eliminate White Flies on Tomato Plants

Tomato plants are susceptible to infestations by white flies, which are small sap-sucking insects. These pests have become resistant to many synthetic pesticides, making chemical control challenging. However, there are proven organic techniques that can help you get rid of white flies. In this article, we will explore effective methods to control these pests and protect your tomato plants.

What are White Flies?

White flies, although called “flies,” are not true flies. They are winged insects that belong to the order Hemiptera, closely related to aphids, mealybugs, and scale insects. These small insects, about 1/12 of an inch in size, have soft bodies and a somewhat triangular shape. They are usually found in groups on the undersides of leaves and are active during the day.

Identifying White Flies

Adult white flies are moth-like insects with powdery white wings and short antennae. They are easily recognized and often found near the tops of plants or on stem ends. Wingless nymphs, on the other hand, are flattened, oval, and almost scale-like in appearance. Like aphids, whiteflies drink plant sap using their sharp piercing-sucking mouthparts, and they secrete a sticky substance called honeydew. The presence of honeydew can lead to the growth of black sooty mold on leaves.

Life Cycle of White Flies

White flies have a life cycle that consists of several stages. Young nymphs overwinter on the leaves of host plants, while adult females deposit 200-400 eggs in circular clusters on the undersides of upper leaves in late spring. The eggs hatch in 5-10 days, and the nymphs move a short distance from the egg before attaching themselves to the underside of leaves to feed. After going through several nymphal stages, a non-feeding pupal stage follows, and within a week, young adults emerge to repeat the cycle.

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Host Plants and Infestation

White flies can infest more than 250 ornamental and vegetable plants. Common host plants include tomatoes, citrus, squash, poinsettias, potatoes, cucumbers, grapes, and hibiscus. Infestations are common in southern and coastal states, where white flies can be found year-round in outdoor gardens. In northern areas, year-round infestations are possible only indoors.

Detecting White Flies on Tomato Plants

White flies typically prefer to feed on new growth, so carefully inspect the vicinity of freshly unfurled leaves on your tomato plants. Check the undersides of leaves, especially around the veins, for the presence of white insects. It can be challenging to spot them due to their small size. Sticky honeydew on the surfaces of leaves is another indicator of white fly activity. If disturbed, white flies will suddenly swarm and fly off the leaves.

Effective Control Methods

To control white flies effectively, use proven organic techniques. Here are several methods to consider:

  1. Yellow sticky traps: These traps are useful for monitoring and suppressing adult populations of white flies.
  2. Hosing off plants: Use a strong stream of water from a hose to remove white flies from plants and reduce pest numbers.
  3. Beneficial insects: Introduce natural predators such as ladybugs, green lacewings larvae, and whitefly parasites to control white fly populations. Make releases when pest levels are low to medium for best results.
  4. Attract natural enemies: Create a habitat that attracts natural enemies of white flies, such as dragonflies or hummingbirds. These creatures can help control white fly populations.
  5. Least-toxic organic pesticides: If white fly populations are high, use short-lived organic pesticides to establish control. Once beneficial insects have been released, it is not recommended to use insecticides as they may harm these natural predators.
  6. Reflective mulch: Apply aluminum reflective mulch, especially around vegetable crops like tomatoes and peppers, to make it difficult for white flies to locate their preferred host plants.
  7. Safer® Soap: This natural pesticide works by damaging the outer layer of soft-bodied insect pests, causing dehydration and death within hours. Apply it when insects are present, following the recommended dosage.
  8. BotaniGard ES: This highly effective biological insecticide contains Beauveria bassiana, an entomopathogenic fungus that attacks various crop pests. Weekly applications can prevent insect population explosions.
  9. Organic Neem Oil: Spray Neem Oil on affected plants to kill white fly eggs, larvae, and adults. Ensure complete coverage of all leaf surfaces.
  10. Horticultural oils: These oils smother insects and are highly effective against all stages of white flies.
  11. Botanical insecticides: Use fast-acting, plant-derived insecticides as a last resort. These natural pesticides have fewer harmful side effects and break down quickly in the environment.
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To avoid attracting ants, which feed on honeydew produced by white flies, apply Tanglefoot Pest Barrier to the stalks of roses and other woody plants.

By implementing these effective control methods, you can safeguard your tomato plants from white fly infestations and ensure healthy growth and high yields.

Remember, if you need additional guidance or have concerns about white flies, consult with a professional horticulturist or a local agricultural extension service.

For more information on gardening, plant care, and pest control, visit Ames Farm Center.

Whiteflies under magnification