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a collection of twospotted mites on a green background. twospotted mites are a major pest on more than 200 species of plants

Controlling insects naturally

Summer is the season… for checking landscape plants for insects before they devour your plants with their ravenous appetite.   Conservative estimates state there are over 12,000 species of insects in Florida, so it’s no wonder your hibiscus might look like it was the main course at an insect dinner party!

Even though less than 1% of insects are truly ‘pests’, most people prefer to not see insects inside or outside their home. In the past, conventional pesticides were the ‘go to’ for eliminating unwanted insects. Unfortunately, our dependency and overuse of pesticides has resulted in insect resistance and detrimental outcomes to non-target organisms.

This is where Alternative pesticides come in. Alternative pesticides, or natural pesticides, are those products typically derived from materials produced from animals, plants, bacteria, or certain minerals. They tend to pose fewer risks than conventional chemicals.  Typically only small quantities are needed and they break down more quickly which is good for the environment.

Natural Insecticides

Sample oil products for pest control. Photo by Mary Derrick.

Horticultural oils are a prime example. Commercially available horticultural oils are mineral oils from refined petroleum products. These compounds were developed as a safer way to treat pests on fruit trees. Diluted and sprayed on plants at various times of the year, they act to suffocate or starve insects, especially soft-bodied pests like aphids and mealybug. Horticulture oils can burn plants in our summer sun, so be sure to read the label before applying.

Example of Insecticidal Soap.

Similarly, insecticidal soaps are diluted, soapy mixtures sprayed on plants to kill insects by suffocation, starvation or simply drying out the insect from the inside out.

So, where you might hear someone say to “use soap or oil” to control insects, just keep in mind it doesn’t refer to simply pouring dish soap or baby oil around your garden. These are specifically formulated products that have been tested and proven to work when applied according to label instructions.

Natural pesticides also come in the form of microbial insecticides such as Bacillus thuringiensis (“Bt”) and spinosad. Made from naturally occurring bacteria, these products affect the digestive and nervous systems of insects that eat or touch them, killing them in the process.

Natural Herbicide

If you have a problem with weeds just look in your kitchen cabinet for a great, natural pesticide: vinegar! Household vinegar is 5% acetic acid and will work against weeds, but multiple applications will be needed to kill the weeds. Commercially available vinegar (20-30% acetic acid) will kill unwanted weeds in one application. Be sure to use caution when using either concentration, since vinegar is non-selective. A high-enough dose of vinegar will kill whatever plant it touches.

And that leads to a final point: nothing is perfect and nothing is completely harmless. Use natural pesticides with the same caution as with conventional pesticides. Always read the label before applying any product. Even a natural product can cause harm if used improperly.

The best advice remains to only use a pesticide:

  • when the benefits outweigh the risks
  • they are used as part of an integrated pest management plan and
  • only after non-chemical pest control procedures have failed

Click on the link below for more information on alternative pesticides for landscape and garden pests:

Natural Products for Managing Landscape and Garden Pests in Florida

2 Comments on “Controlling insects naturally

  1. Concerned about grasshoppers eating our palm fronds. This our second summer her from Maine. What should we do or not do.

    • Hi Sherry – since I’m not sure what type of grasshopper it is, would you be able to send a picture to the plant clinic for identification? ( The large Eastern lubber may be the culprit, but I would need to know more about the insect to give you proper guidance. They usually do not eat enough to cause any permanent damage, but not sure if this is the case with your palms. Lubber adults are usually found during July and August. I am happy to help, please contact our office directly so we can discuss the insect problem.