How Biodiversity Naturally Keeps Pests in Check

After spending many hours tending to your cabbages, broccoli, or kale, you visit your garden one morning to find them riddled with holes, taken over by an army of slugs. 

Any gardener, beginner or experienced, knows the struggle of keeping pests at bay and the large amounts of money that can wind up being spent to rid them out. Fortunately, biodiversity is one of the best ways to naturally protect your garden from creepy crawlers. 

What is Biodiversity?

Biodiversity consists of three main types, that is, genetic, species, and ecosystem. Ultimately, it is about the abundance of different life forms in an area, which includes more than just plants and animals but also fungi and microorganisms. These organisms interact with one another in an ecosystem to maintain balance and support the flourishing of the ecosystem. 

How Does Biodiversity Help with Pest Control?

The abundance and range of different species interacting in an ecosystem prevents the mass takeover of a certain pest—think of the spider's role in catching mosquitoes with its web. 

In the garden, where you have the same monotonous vegetables planted in rows such as cabbage, cucumbers, and tomatoes, you can wind up attracting more pests than beneficial insects, resulting in your garden becoming a grocery market for aphids, slugs, earwigs, cucumber beetles, and Japanese beetles. 

The garden is an ecosystem, and healthy ecosystems require a variety of species. Beneficial insect species you may want to attract include:

• Ladybugs, green lacewing, and hoverflies- these species are particularly useful for attacking aphids. A single ladybug can eat up to 5,000 aphids in its lifetime, a staggering amount.  

• Ground beetles- known to eat slugs, nematodes, and caterpillars. These are useful for guarding young seedlings. 

• Soldier beetles- useful for attacking potato beetles, caterpillars, and aphids.

• Assassin Bug- great for eating squash bugs.

• Parasitic wasps- which may sound intimidating, but are useful for hornworms, Japanese beetles, and squash bugs, as they lay their eggs in or on the host pest, eventually killing it.

How Does Biodiversity Help with Pest Control?

The abundance and range of different species interacting in an ecosystem prevents the mass takeover of a certain pest—think of the spider's role in catching mosquitoes with its web. 

In the garden, where you have the same monotonous vegetables planted in rows such as cabbage, cucumbers, and tomatoes, you can wind up attracting more pests than beneficial insects, resulting in your garden becoming a grocery market for aphids, slugs, earwigs, cucumber beetles, and Japanese beetles. 

The garden is an ecosystem, and healthy ecosystems require a variety of species. Beneficial insect species you may want to attract include:

• Ladybugs, green lacewing, and hoverflies- these species are particularly useful for attacking aphids. A single ladybug can eat up to 5,000 aphids in its lifetime, a staggering amount.  

• Ground beetles- known to eat slugs, nematodes, and caterpillars. These are useful for guarding young seedlings. 

• Soldier beetles- useful for attacking potato beetles, caterpillars, and aphids.

• Assassin Bug- great for eating squash bugs.

• Parasitic wasps- which may sound intimidating, but are useful for hornworms, Japanese beetles, and squash bugs, as they lay their eggs in or on the host pest, eventually killing it.

How To Attract Beneficial Species and Repel Unwanted Visitors 

Planting more flowers such as marigolds, calendula, and sweet asylum can attract beneficial insect species that reduce pest populations. Aromatic herbs like dill, basil, chives, lemon balm, cilantro, and fennel are also incredibly useful. However, I would suggest being cautious with mint, a commonly suggested herb, as it spreads like wildfire in the garden, becoming difficult to eradicate.    

It is recommended to plant smaller plants on the edges of your beds and the spaces between crops. It is also a good idea to plant flowers and plants of different heights and shapes for a diversity in beneficial species. Companion planting can be used to plant certain species next to vulnerable crops to help benefit them. Here are some examples of how companion planting can be used in your garden: 

• Catnip- repels flea beetles and potato beetles; plant next to peas and potatoes

• Borage- deters cabbageworm and hornworms; plant next to cabbage and tomatoes

• Calendula- attracts pollinators and repels asparagus beetle; plant next to tomatoes, cucumbers, asparagus, peas

• Chives- attracts pollinators, repels Japanese beetle, carrot fly, aphids; plant next to carrots, broccoli, cabbage, strawberries

Ultimately, the more plant species you have in your garden, the more beneficial species you will have, and the healthier your garden ecosystem will be. Don’t be afraid to experiment by planting different varieties to see what happens!

Happy Gardening!  

Sources:

Hancock, L. (2025). What is biodiversity?. WWF. https://www.worldwildlife.org/pages/what-is-biodiversity#:~:text=Biodiversity%20is%20all%20the%20different,maintain%20balance%20and%20support%20life. 

Rhoades, H. (2021, July 23). Tips To Attract Ladybugs To Your Garden. Gardening Know How. https://www.gardeningknowhow.com/garden-how-to/beneficial/attract-ladybugs.htm 

Sweetster, Robin. (2025, February 10). Beneficial Insects in the Garden. Farmers Almanac. https://www.almanac.com/beneficial-insects-garden 

Barbars. (2025, January 2). 3 Hidden Ways Biodiversity Makes Your Garden Thrive (And Why It Matters). Bluestem Gardening. https://bluestem.ca/wildlife-and-biodiversity/3-hidden-ways-biodiversity-makes-your-garden-thrive-and-why-it-matters/ 

Gardenia. (n.d.). Companion Planting and Attracting Beneficial Insects to Your Garden. https://www.gardenia.net/guide/wonderful-plants-that-repel-insects