Whiteflies: How To Get Rid Of Whitefly In The Garden

Whiteflies on underside of plumeria leaves via Scot Nelson

Whiteflies on underside of plumeria leaves via Scot Nelson

Whiteflies, those small winged insects that settle under part of plant leaves in clusters, use their small size (1/12 of an inch) as a strategy for camouflage. These winged insects share a close relation to aphids.

The Species Of Whiteflies

Various species of whitefly exist usually identified by the plant you find them on. Let’s look at a few:

  • Greenhouse Whitefly – the most common, found mostly on fruit, vegetables and ornamental or garden plants.
  • Citrus Whitefly –  Aleurocanthus woglumi – attacks citrus crops
  • Cabbage Whitefly – scientifically named Aleyrodes proletella – as the name suggests the pest attacks the brassica species which include cabbages.
  • Silverleaf Whitefly – attacks poinsettia, also tomato, peppers, squash, cucumber, beans, eggplant, watermelon, and cabbage and over 500 other species of plants

Identifying Whiteflies In The Garden

When whiteflies infest a plant, you’ll find them in “swarms” ingesting the plant juices. They then secrete “honeydew”, making the top and bottom of leaves sticky or covered with a black sooty mold.

The ultimate result of these sticky, sooty mold formations weakens the plant and hinders photosynthesis production. This leads to a withered plant as leaves begin to become dry, turn yellow and finally fall of the plant.

When you check under the affected leaves the pests have pricked and eaten the veins. Though difficult to view with the naked eye, when touching the leaf you can “feel” the honeydew on the surface. [source]

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For a quick way to check for the presence of whiteflies, shake the plants to see if the white fly swarms in large numbers. Also look where leaves appear whitish and losing their aesthetic value in the garden.

Natural Ways To Control Whiteflies

#1 – Implement the use of natural predators to control whitefly indirectly by planting flowering plants that attract predators such as lady beetles and lacewing larvae that will feed and control the whiteflies.

#2 – Sometimes controlling the pest requires other ways to effectively and naturally control them. Try utilizing yellow sticky traps on tomatoes, potatoes, cabbages and pepper plants. Make your own, by mixing  petroleum jelly with a hand washing soap. Apply the mixture to strips of boards painted yellow. The color attracts the white fly leaving them stuck on the strips.

#3 – Use of an aluminum reflective mulch produces a reflection that deters the flies from attacking the plants.

#4 – For a minor infestation, blasting plants with a strong jet of water to chase the whiteflies away. The water can also clear up other unwanted garden pests like aphids.

As mentioned above intermixing plants and flowers can attract an abundance of other beneficial insects for biological control. However, if you notice an increase of whiteflies avoid planting some host plants such as a lantana bush, hibiscus plants and salvia where whitefly hang out.

The Advantages Of Natural Methods Include:

  • Pest control without harming the plant
  • Environmentally friendly
  • Cheap and cost effective when done with commonly available items.

For example, using Nasturtiums as companion plants to “protect” tomatoes and gooseberries. Zinnias, Bee balm and Pineapple Sage attracts predators like hummingbirds, flies and wasps that eat whiteflies.

The use of insecticidal soap, Neem insecticidal oil spray, and even Horticultural oil can provide an effective way of eliminating the pest from your garden.

Using Insecticides For Whitefly Control

The use of chemical insecticides initially controlled the pest well. However, over time these sucking pests developed a resistance to some pesticides. Plus the use of synthetic chemicals is regarded as unfriendly with associated negative environmental effects.

Most chemical pesticides produced in the lab and used to control pests harm the environment. Some kill other helpful insects, do not biodegrade and remain on the leaves and fruits.

Use chemical insecticides only when heavy infestations occur and the pest turns out to be pesticide resistant. In such a case, a variety of insecticides may need to be applied until the insect is eliminated.

Before embarking on natural control of whiteflies, start with a “clean” plant using something like neem or insecticidal soap.

The Life Cycle Of Whiteflies

Females lay 400 whitefly eggs on the underside of leaves. Eggs take 5-10 days to hatch, which look like mealybugs. They don’t move much but stay where they feed for growth. Considering the high percentage of the eggs that hatch effectively into adults this explains why the pest can infest a wide area in a short period of time. From laying of eggs to adult takes about 25 days.

If whitefly population reaches a critical level, consider destroying the plants. Prevention and elimination of whitefly requires regular, proactive inspecting of plants.