Instructions for making homemade mixtures to control pests are easy to find online and in social media, and it's tempting to make your own home remedy when pests invade. Doing so may seem like a natural, organic, and non-chemical solution, but did you know that what you are mixing is considered a pesticide? A pesticide is any mixture used to kill, destroy, repel, or mitigate a pest.

Pesticide mixtures of household ingredients like dish soap, garlic, and vinegar (Figure 1) may seem harmless and safer than storebought formulated pesticides, but they can actually pose unrealized risks.

What is the Concern with Homemade Pesticides?

While ingredients in home remedies are items we might eat or use in the kitchen, the mixture of them is not tested for

Figure 1. Pesticides made from household ingredients lack the details needed to safely and effectively control pests. (Credit: B Messenger-Sikes)

For example, some online sources describe making a homemade insecticide from the tobacco leaves found in cigarettes and tout it as “natural” or “organic.” While cigarettes are readily available for purchase, the resulting concoction (a pesticide) made from tobacco is extremely concentrated and highly poisonous to humans and pets. There are many additives used in producing products such as cigarettes, soaps, or detergents and these ingredients are not always known to the consumer.

Another concern is the potential hazard created during the mixing and making of home remedies. Even while natural, some ingredients become more toxic during the process of cooking the mixture, which may concentrate the ingredients and increase risks of harmful health side effects due to inhalation of fumes or contact with skin.

No Instructions for Use

Commercially available pesticides (Figure 2) are required by law to have a label with instructions on use, mixing, storage, and first aid. Home remedies don't have instructions for specific dilution or use rates, nor do they identify how often mixtures should be applied. Home remedies also contain no guidance about wearing protective equipment like gloves or how to properly store the mixture.

Homemade mixtures are stored in containers that are either not labeled with what's inside or lack the required label information registered pesticides contain. Each year, poison control centers report poisonings of children and adults from drinking pesticides that have been stored in food or drink containers. Without a label and knowledge of how a mixture can affect people when exposed, first aid information isn't available. To prevent accidental poisoning, pesticides should never be mixed or stored in food or drink containers even if the container is marked.

Figure 2. Commercially available pesticides made from botanical extracts.

Are home remedies effective?

Because homemade pesticides vary greatly in their makeup and are not tested through rigorous research studies, there is no data to support whether they consistently control targeted pests. Unlike commercial pesticides that must show their efficacy data before being registered, homemade remedies lack scientific studies to show that they are effective.

Applying ineffective homemade pesticides can make pest problems worse, may not control the pest, could be harmful to the plant, or contaminate waterways. In addition, a homemade pesticide sprayed in the garden may kill the “good bugs” as well as the targeted pest insects. Many commercial pesticides are formulated to work only on specific pests or groups of pests.

Many home remedies specify using dish soap mixed with other ingredients to kill insects, plant diseases, or weeds. Dish soap, which is a powerful detergent, can injure desirable plants by stripping the waxy layer off the leaves. Commercially available insecticidal, fungicidal, and herbicidal soaps, which are registered pesticides, are highly effective against the targeted pest and will not damage plants when used correctly. These products cannot be made at home with common household ingredients.

Are home remedies legal?

The U.S. Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) covers the use of homemade pesticides. According to FIFRA, in order to legally apply a material as a pesticide it must be either registered with the Environmental Protection Agency (EPA) or be exempt from registration. There is a list of active ingredients (the part of a pesticide that affects the pest) that can be used in pesticide products without requiring registration; these are called minimum risk or 25(b) products) The active ingredient list allows the use of single chemicals, like sodium lauryl sulfate (found in soap), as unregistered pesticides, but does not include commercial products like dish soap that may contain other ingredients, such as viscosity modifiers, preservatives, and pH adjusters.

Alternatives to pesticides

Many pests in the home and garden can be managed without pesticides. In a garden, grow plants suited to the environment and keep them healthy with proper irrigation and fertilization. Weeds can be controlled by hand-pulling, mulching, or weeding tools. For more information, see the UC IPM Home and Garden pages.

[Original article published in the Spring 2021 issue of the Retail Newsletter.]