On their own residential property, Americans cumulatively use 67 million pounds of pesticides every year—that’s more per acre than is used for agricultural purposes.1
Biopesticides are derived from natural sources such as plants and animals, unlike more commonly used pesticides that are composed of synthetic chemicals. According to the EPA, “Biopesticides are usually inherently less toxic than conventional pesticides,”2 so they offer a solution for gardeners who are looking for a way to keep pests away without damaging their plants, the soil, or beneficial organisms. Whenever possible, you should look to natural solutions for ridding your home and garden of pests, and biopesticides are one of your many options. There are many different types, and it can be a challenge to find the one that works best for your situation. However, it’s worth the extra time and effort to insure your garden won’t be flooded with indiscriminate poisons. Only apply these products where the problem is most severe, so you leave some pests for the predatory insects that will continue to keep the population in check. Remember, even if it is a natural product, a biopesticide can still be dangerous to your family or pets if misused, so be sure to read all labels carefully, and seek additional assistance whenever needed (i.e., call in the professionals, but make your desire for natural alternatives clear).
Soapy water is an excellent way to kill most small pests. Simply shake it up in a spray bottle and apply, while being careful to avoid beneficial critters.
Neem oil repels a wide variety of pests, but is harmless to lady beetles, honeybees, and butterflies.
Garlic oil kills pests and beneficial organisms indiscriminately, but is harmless to human beings. Use it only for insects when they remain unchecked by natural predators.
Citrus Peel Extracts such as limonene and linalool are useful for eliminating aphids, fleas, mites, fire ants, and various other pests.
If you see a snail or slug consuming your vegetables, just pour on some salt, which will cause them to shrivel on the spot.
Diatomaceous earth is a mechanical pesticide, not a chemical one. It is made from the fossilized remains of hard-shelled algae. Unfortunately, since it is deadly for all arthropods, it will kill helpful insects as well as harmful ones.
If you have a cockroach problem, try boric acid. This can by applied as a powder that will last for up to a year indoors. Don’t be fooled when the cockroaches haven’t started dying after a couple of days. Unlike harsh chemicals that kill pests immediately, boric acid can take 5–10 days to be effective, but the results will last noticeably longer.3
Sulfur is toxic to arthropods, but much more so to mites than to insects, making it a great option if you want to keep the beneficial predatory insects alive. It is also effective against various plant diseases.
If it looks like a fungus has taken hold of your favorite plant, mix a few teaspoons of baking soda with water in a spray bottle and apply.
Corn gluten meal will kill weeds BEFORE they grow if applied to clear soil. Be careful to avoid the soil very near the plants you want to keep growing.
Vinegar or boiling water can be poured directly onto an unwanted weed to destroy it.
Nosema locustae (sold as NOLO Bait and Grasshopper Attack) will infect and kill grasshoppers and other closely related insects, but will leave all others unharmed.
Milky spore is useful against the grubs of the Japanese beetle. Apply it in late summer when the grubs are beginning to feed.
Bacillus thuringiensis (BT) is a bacteria that infects various kinds of caterpillars. You’ll find their remains hanging upside down from plants for days after application.4 Some strains will also kill the larvae of certain mosquitoes and black flies.
1 Allison Knab, “Natural Pest Control,” Chicago Wilderness Magazine, Spring 2005, http://www.chicagowildernessmag.org/issues/spring2005/natpestcontrol.html (accessed December 8, 2010).
2 “What are biopesticides?” The Environmental Protection Agency, http://www.epa.gov/oppbppd1/biopesticides/whatarebiopesticides.htm (accessed December 8, 2010).
3 William Olkowski, Sheila Daar, Helga Olkowski, Common-Sense Pest Control, (Newtown, CT: Taunton Press, 1991).