Sometimes it can feel like we live in constant peril from unnatural chemicals. For example, 45 million pounds of pesticides are used in homes and gardens every year. Confronted with this fact, many people seek out organic pesticides to avoid harming themselves or the environment. How much better or healthier a pest control method is, however, depends on how toxic it is—not on whether the source is organic or man-made.
What does organic mean in this context?
Many people enjoy pointing out that, on our planet full of carbon-based life forms, a huge range of things are technically organic, since they are made of molecules with at least one carbon atom. But for the purposes of pest control, organic is defined as “using a means of control that does not use man-made chemicals.” Organic pest control typically involves natural substances that range from soaps, salt and vinegar to pyrethrum and lime sulfur.
Is organic more expensive?
While organic versions of produce, meat, fabrics and household goods are typically more expensive, this does not always apply to pest control. Some organic pest control solutions are more expensive, while others are less so.
An informal survey of pest control sprays online indicated that organic sprays cost between two and four times as much as conventional ones. One retailer, for instance, has a 64 ounce bottle of organic pest control made with lemongrass oils for $10.27 (16 cents per ounce) while offering a 1.33 gallon bottle of conventional insecticide for $14.97 (8 cents per ounce).
However, home organic pest control solutions include a number of inexpensive options. The very cheapest is boiling water, which costs only as much as the energy to heat it. White vinegar is frequently recommended as an herbicide and sells for under $3 per gallon.
The price of any pest control option is compounded by how often it must be applied to be effective. In the case of some conventional options, application is necessary as little as once a year indoors on non-porous surfaces. Some organic ones last several weeks between applications; others only work on contact when the product is wet.
Is organic safer?
The National Pesticide Information Center says that it is more important to consider the toxicity of a substance than it is to consider whether or not it is organic. A number of chemical pest control agents are minimally toxic to humans and disperse quickly to prevent dangerous exposure.
Some organic pesticides carry risks. For instance, plant oils used in some organic pesticides irritate eyes and other mucus membranes. A number of people may find that they are allergic to these ingredients.
Organic pesticides sometimes contain metallic substances like sulfur and zinc. These can contaminate surface water and damage equipment when not used properly.
In some cases, the question becomes, “safer for whom?” Pyrethrins are extracted from chrysanthemums, with only a small level of toxicity to humans. However, they kill both beneficial and harmful insects alike. Also toxic to fish and amphibians, pyrethrum-based pesticides should not be used in areas where they may wind up in waterways or storm drains. Vinegar, while harmless to most humans, can affect many different kinds of plants if used as a herbicide. While pre-emergent chemical herbicides affect only a blossoming plant and soon dissipate, substances like salt can stay in soil for extended periods of time and inhibit growth of both desirable and undesirable plants alike.
Research into organic pest control continues to develop just as conventional pest control research does. Certain once-popular organic options have been discontinued because of newly understood dangers. While tobacco was once widely used to inhibit garden insects, even tobacco dust is now forbidden in organic agriculture because of toxicity. Arsenic and strychnine were also used in the past but are no longer recommended for organic pest control.
Many consumers look to organic pest control out of concern for declining bee populations. Just because a product is organic, however, doesn’t mean that it’s safe for bees. The following organic pest control agents have been shown to be unsafe for bees:
- Diatomaceous earth. This soft sedimentary rock is made of small crystals that lacerate insects’ bodies. While it can effectively kill pests like cockroaches and fleas, it can also harm bees.
- Pyrethrins. All pesticides in this family are harmful to flying insects.
- Rotenone. Derived from the seeds and stems of plants in the same family as the jicama vine, this substance is harmful to bees and fish. It is also mildly toxic to humans and has been tenuously connected to the development of Parkinson’s disease.
- Spinosad. Made from the soil bacteria Saccharopolyspora spinosa, this substance is harmful to all insects, including bees.
There are, however, a number of organic pest control methods that can be used without risking bee populations. A few that have low toxicity or are non-toxic:
- Boric acid
- Kaolin clay
- Neem oil
- Limonene, a solvent derived from the skins of citrus fruits.
- Ryania, an insecticide made from the ground stems of a tropical plant.
Which works better?
In many cases, conventional pest control options are more effective than organic ones and can be used less often to get the job done. For instance, the National Center for Food and Agriculture Policy says that copper, when used as an organic fungicide, must be used at a rate of four pounds per acre. Sulfur must be used at a rate of 34 pounds per acre. Chemical fungicides, by contrast, can be used at a rate of 1.6 pounds per acre to generate the same result.
But in other cases, organic pesticides can be more effective than chemical ones. Biopesticides, which are made from living things or are found in nature, are often organic and carry lower risks while being more effective. Some biopesticides are targeted and work on only a small number of species. Others only affect the targeted organism for a short period of time and then break down quickly to reduce the risk of pollution. A few effective biopesticides that can be produced organically:
- Microbes. Fungus and bacteria can be used to control weeds and insects without having a negative effect on the environment.
- Plant materials. Garlic oil, black pepper and corn gluten all break down quickly after use.
- Hormones. Insect hormones, such as those that regulate mating behavior, can alter the way that a pest acts without killing it outright. For instance, a hormone that is used on moths may prevent them from mating or engaging in food-finding behaviors.
- Plant-incorporated protectants. These are genes and proteins that are introduced into plants through genetic engineering. These are rarely considered organic, as they fall under the umbrella of GMOs.
Biopesticides are often used as part of an integrated pest management approach that is more effective than using any one means of control alone.
Some organic options, such as companion planting, can be highly effective when used in conjunction with other methods. For instance, planting chrysanthemums in a bed with other plants can keep pests away from them in the garden. Other companion plants that may repel pests include rosemary, onion and thyme.
A third option: minimum-risk pesticides
If you are looking for ways to control pests around your home and garden while also controlling your risk, it may be better to consider the pest control options known as “minimum risk pesticides.” While they may not be organic, they are the options that are the least toxic. These pesticides, because of their low risk, do not need to be registered with the EPA before sale. To qualify as a minimum risk pesticide, a product must satisfy all of these requirements:
- contain only the active ingredients on the minimal risk list.
- contain only other ingredients that are on a list of safe additives.
- make no misleading label claims.
- must identify all ingredients on the product label.
- must not claim to control pests that can impact anyone’s health.
Minimum risk ingredients include: garlic oil, cedar oil, citronella, corn gluten meal, lemongrass oil, mint oil, egg solids, salt, soybean oil, zinc metal strips and thyme. While many of these are ingredients that can be produced organically, they need not be organic to make the minimum risk list.
Controlling pests while staying safe
Sometimes the organic option is the safest option. In other cases, a chemical or biological product will be safer even though it is not organic. No matter what pest control products you choose, always remember the following:
- use the least toxic pest control option that will get the job done.
- use products only as labeled. Using larger quantities or using a product in an area that it is not intended for can lead to danger to your health or environmental harm.
- remember that risk is always dependent on the toxicity of the ingredients and the amount of exposure.