Gardening: How to deal with pesky pests

Eileen Ward, Columnist

Our weather allows for insect activity year round. For those of you who prefer to try the natural way of controlling pests in your yard, there is Integrated Pest Management.

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When using Integrated Pest Management in your yard, proper identification of insects is a must. There are many books available with pictures and information on the insects of Florida. A very good one is titled "Florida Insects" and costs around $5. It's available in the local garden center or hardware store. The Collier County Extension Office in Immokalee also has excellent literature on Florida insects, and the internet has an endless supply of information.
Learn the beneficial insects, which will feed on the harmful pests, and learn to recognize when they are doing their job. If aphids, scale or whitefly nymphs have a small pin-hole, they have been parasitized by a tiny parasitic wasp. If predators are found, every effort should be made to preserve them. Allow the beneficial insects to control the pest population before applying insecticides. Most plants in the landscape are over-sprayed, resulting in unnecessary environmental contamination and often upsetting the natural predator/pest balance. Spray only when a pest population is present and damage is beginning to occur.
Pests of ornamentals are grouped according to the way they damage plants:

  • Insects With Piercing-Sucking Mouthparts: They have beak-like mouthparts used for piercing the plant tissue and sucking plant juices. Examples include scales, aphids, whiteflies, mealybugs, thrips and lace bugs.
  • Foliage Feeding Insects: They feed on the leaves, flowers or roots. Examples include caterpillars, beetles and grasshoppers.
  • Spider Mite: These pests are not insects, but closely related to spiders and scorpions. They suck plant juices with piercing-sucking mouthparts.
  • Leafminer: These are small larvae of flies, beetles or moths that tunnel between leaf surfaces.
  • Borers: These are either the larvae of moths or beetles which bore into twigs and trunks of plants.

If a population of pests gets out of control, use a garden hose and direct a strong spray of water at the stems and undersides of leaves of the plant to lower the pest population.
If you do have to spray insecticides, use the less-toxic products such as Insecticidal Soap or Neem Insecticide, a derivative of the Neem tree, which acts as a reproductive and feeding inhibitor/disrupter and growth regulator. Pyrethrins from chrysanthemums will paralyze and kill insects. Additional options are a product line using potassium salts of fatty acids which penetrates the outer shell of soft bodied insect pests causing dehydration and death within hours, oils which smother the insects and Bacillus thuringiensis, Dipel or Thuricide, a natural bacterium for control of moth or butterfly larvae.
Insecticides may be required to control pests when they reach damaging levels on the plants. Before using a chemical insecticide you should consider the following points.

  1. Select the right material: Use only an insecticide that is recommended to control the target pest and is safe on the host plant.
  2. Use the right amount: Too little won't control the pest, and too much may injure the plant. Read the label for the correct dosage rate.
  3. Apply it in the right way: Thorough coverage of leaves, especially the underside of twigs and branches, is essential. The insecticide must reach the area where the pest is feeding. Use of a spreader sticker will aid in the pesticide adhering to the leaves for better coverage and control.

There is no one spray that will control all pests of ornamentals. There may be times when you will need to treat with additional insecticides to control different pest infestations on the same plant.
Systemic insecticides are absorbed by the host plant and trans-located throughout the plant tissue which makes the plant toxic to certain mite and insect pests for up to six weeks or months. They can be taken up by the roots when applied in granular form or absorbed by foliage or stems using sprays or injections. Systemic insecticides are effective in controlling sucking pests and mites; they do not give satisfactory control of chewing insects. Talstar or Merit are examples of systemic insecticides.
Malathion is also effective for controlling sucking insects. Sevin controls a wide range of chewing insects. Kelthane controls mites. Lindane is no longer available for borers and leafminers, so you will have to read labels to find a replacement. Also read the labels to identify which plants these sprays can be safely used on.
Phytotoxicity, or plant injury, can be caused by certain pesticides on certain plants. The degree of injury can be affected by conditions like temperature, humidity and other environmental factors. It is best to apply pesticides during the cooler part of the day; plants are less likely to be injured when protected by partial shade as opposed to being in direct sun. Some materials can injure plants that are stressed for moisture, so plants should be well watered a day or two in advance of being treated with insecticides.
And remember: READ THE LABEL.

Eileen and Peter Ward have owned a landscape and lawn maintenance company for 35 years. Eileen can be reached at or 239-394-1413.