The most effective pest control methods: Physical, biological and chemical

Key points

• Physical, biological and chemical methods are the three main types of pest control.

• Integrated pest management (IPM) encourages a comprehensive plan that combines pest control methods.

• Determining the best pest control method requires identifying your pests and creating a treatment plan.

There are three main pest control methods to choose from when you encounter a pest problem — physical, biological and chemical. Depending on the type of pest, their locations and your goals, you may use one of these methods or a combination of the three.

Physical methods involve creating barriers and using methods of exclusion. Biological methods include using “living organisms to manage pest populations,” according to Jana McDaniel, founder of First Saturday Lime, an eco-friendly insect repellent. Chemical pest control uses pesticides such as rodenticides and insecticides to control unwanted visitors.

Understanding the type of pest you’re dealing with will help you determine the proper pest control method. It’s also crucial to employ each method properly to avoid harming unintended victims, whether they’re “good” bugs or family pets.

Blair Calder, founder and CEO of Automatic Trap Company, warned that rodenticides, for instance, don’t have an antidote, a fact which “comes as a shock to thousands of pet owners every year in the U.S. when their dog or cat is accidentally poisoned by eating a dead rat or mouse that has been exposed.”

Below, we dive into more detail on the most common pest control methods, how they work together to control pests, and how to use them safely.

What are the most common pest control methods?

The most common pest control methods fall under three categories — physical, biological and chemical. Some of these are good DIY methods, while others should be done by qualified pest control services.

• Physical methods include creating barriers, setting traps, applying deterrents and physically removing the pests.
• Biological methods include using natural predators, parasitoids and microbial agents to kill unwanted pests.
• Chemical methods include applying pesticides or rodenticides targeted to the pest you’re having issues with.

These methods can be used in isolation or in conjunction with each other as part of an Integrated Pest Management (IPM) plan, depending on the level of infestation and the goals of removal. For instance, introducing predatory insects with certain plants can be a self-sustaining pest management plan while trapping pests requires more active management.

What are physical pest control methods?

Physical, or mechanical, pest control methods include creating barriers, using exclusion methods, introducing deterrents, placing traps and using suction to remove unwanted pests from the target area. Essentially, physical pest control seeks to use methods that actually remove pests from the space or keep them out altogether, so other methods — biological and chemical — aren’t necessary.

Barriers and exclusion

Calder described barriers and exclusion as “the best form of pest control,” adding that “if rats and mice cannot physically enter a location, it’s perfectly safe from infestation.” The problem with this, however, is that it’s “simply impossible for a lot of facilities.” Mice, for example, can enter a space through a hole the size of a dime, making it incredibly difficult to fully rodent-proof a building.

Traps and capture devices

Various traps and capture devices are available for use on rodents and insects. These require active management to empty or replace as needed. Traps can be used to capture rodents, which you must then dispose of. Other mechanical traps include sticky paper to collect unwanted insects.

The type of trap you choose should be targeted for the specific pest you are trying to control. Unfortunately, traps and capture devices can also capture beneficial insects, so it’s best to talk with a qualified professional before using this method. They also aren’t the most humane.

Deterrents

Applying deterrents or repellents to an area to keep pests away can be an effective pest management strategy. Insecticidal soaps, for instance, can be applied around the garden to ward off would-be invaders. Certain oils such as peppermint, foods such as garlic or mint, and plants such as marigolds can also be effective at keeping unwanted pests away from your yard or garden.

Mechanical removal 

Mechanical removal methods include hand-picking insects off of plants or removing them with a stream of water. You can also use an insect vacuum to remove insects and eggs from plants with strong leaves or shake the plants and vacuum the insects out of the air.

What are biological pest control methods?

Biological pest control methods use natural predators, parasitoids and microbial agents to kill pests. While you can do some of this on your own, such as planting native plants to attract native predators, you should contact a pest control company to help determine whether parasitoids, parasitic nematodes or microbial agents are the best route to effective pest control.

Predatory insects and invertebrates

Inviting more insects and invertebrates into your yard, garden or home may seem counterintuitive, but this method of pest control can actually help reduce unwanted pests as well as the need for chemical pesticides.

Many animals have natural enemies — other insects or animals that naturally prey on them — and you can use this to your advantage. For example, planting native plants can attract ladybugs that eat harmful aphids. McDaniel said these are “best used as a preventative measure or for minor infestations.”

Parasitoids and parasitic nematodes

While you can attract insects and invertebrates that feed on harmful yard pests, you can also attract parasitoids that lay their eggs on or in unwanted pests. As the young develop through the egg, larvae, nymph and pupa stages, they feed on their host, ultimately killing it in the process.

Parasitic nematodes are small, often microscopic, roundworms that feed on a host insect from the inside. Once they’ve killed the host, they will move on to another, and because of this, they can be used to control pest problems.

Microbial agents

Microbial agents are pesticides consisting of a microorganism targeted to certain pest populations. This type of pest control can include bacteria, viruses, fungi and protozoans that can kill an unwanted pest or otherwise make it sick and reduce reproduction rates.

Natural pest control

Certain oils, iron phosphate and diatomaceous earth are also natural methods of pest control that kill a variety of insect populations as well as slugs and snails in the yard or garden.

What are chemical pest control methods?

McDaniel described chemical pest control as “using synthetic or natural substances to eliminate or deter pests.” Pesticide is the general term for chemical pest control methods that include insecticides to kill insects and rodenticides to kill rodents.

These methods should be used cautiously as they are made of poisons that, while intended to remove pest infestations, can also poison humans and other animals, such as pets. Use a pesticide targeted specifically to the pest you’re trying to eliminate when possible. Use chemical pesticides cautiously to avoid harming anything other than the target pest.

Insecticides

Insecticides are chemicals intended to kill certain insect pests. Before choosing an insecticide, homeowners should identify the type of insect they’re trying to get rid of, as different insecticides will control different insect populations. If you’re applying insecticides to a vegetable garden, it’s especially important to pay attention to the preharvest interval — the amount of time you need to wait between applying the insecticide and harvesting the food.

Some examples of pesticides, according to McDaniel, include imidacloprid — which plants absorb, making them toxic to sap-sucking insects such as aphids and whiteflies — and pyrethrin, which will “target a wide range of insects by disrupting their nervous systems,” she said. These are used particularly on mosquitoes, flies and beetles.

Rodenticides

Rodenticides are poisons used to kill rats, mice, squirrels and other rodents, but they are also poisonous to other animals and humans if ingested or if a pet, such as a dog or cat, eats a dead rodent that was exposed to rodenticide.

“Rodenticides are deployed in ‘Bait Boxes,’ plastic containers about the size of a shoebox,” Calder said. Rodents eat the rodenticide inside, which contains an anticoagulant that kills them after one or more feedings by preventing their blood from clotting.

What is Integrated Pest Management (IPM)?

The Environmental Protection Agency describes Integrated Pest Management (IPM) as a continuum that begins with knowing the type of pest you’re dealing with and treating for. Calder said, “The essence of IPM is to take a comprehensive approach, including all factors that contribute to the problem.” IPM integrates multiple pest control methods to prevent pests from becoming a problem and then search out the most effective treatments if they do.

Essentially, IPM uses data, knowledge of pest behavior, biology and technology, and biological, physical and chemical methods to prevent or reduce pest damage. For rats and rodents in particular, “Waste management is the largest element,” Calder said. Cutting off the food supply for rodents can result in their leaving to find a better food source.

One example of IPM, he said, is to combine methods. In the case of rats, you should seal up the building to exclude the pests and then use eradication methods to eliminate any left in the building.

“An IPM approach to managing aphids might involve monitoring plants regularly, removing infested leaves, introducing ladybugs and using insecticidal soaps only if the infestation becomes severe,” McDaniel said.

What pest control safety precautions should you take?

If you’re handling pest control alone, you should take some precautions to ensure the safety of yourself and others in your home. Calder said the first step in handling rodents in the home is to kill them. Once that’s done, dispose of them “the same way you would dog poop — do not touch dead rodents, use plastic bags to pick up and dispose of them,” and then clean up droppings with a broom and spray urine stains and blood with a bleach solution. He also recommended using an N95 mask while cleaning the droppings.

McDaniel said identifying the pest to choose the appropriate pest control method or methods, following label instructions for pesticides, and wearing protective gear when handling chemicals can help you treat the issue safely. She also emphasized keeping children and pets away from the treated areas until it’s safe and making sure to “address underlying issues, like moisture problems or gaps in the home’s exterior, to prevent future infestations.”

Brian Feldman, senior director of technical operations for TruGreen, also emphasized that if homeowners decide to take a DIY pest control approach, “it’s crucial for them to thoroughly read through the product labels from big-box stores to ensure they are using them safely and accurately and plan for the specialized equipment needed to deliver the products safely and effectively.”

What’s next?

If you’ve identified a pest problem in your home or yard, you should first work to identify the pest causing the problem. Treating your home for rodents will require different pest control methods than dealing with insect infestations in your garden, so understanding what you’re up against can give you the best starting point.

“Pest control issues can arise both in and out of the home, and considering how quickly populations can multiply, proactive prevention and treatment are crucial,” Feldman said.

Contacting a pest control company, such as Orkin or Terminix, is a good next step after identifying a pest problem in your home or yard. Pest control specialists are trained in various pest control methods and can offer insights into the best ways to eradicate or control the pests in your home or yard.

McDaniel recommended checking a company’s license and certifications to confirm they can handle the issue. She also said to consider companies that use IPM strategies and have positive reviews from past clients.

“For outdoor pest issues, homeowners should tap a lawn care professional with pest control service program credentials to ensure they are given credible advice to keep their outdoor space healthy, safe and pest-free,” Feldman said.

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