What Chemicals are in plants that repel Insects?

Flies are pesky little critters that are at the least very annoying to have buzzing around you. Luckily, unlike some other flying insects like mosquitos or wasps, they don’t usually bite or sting.

However, make no mistake – flies carry all sorts of diseases, they should be kept away from food and clean surfaces. In this article, we will discuss some natural remedies that can help keep flies away – indoor and outdoor plants.

First, let’s take a look at the common species of flies that you may be assaulted by.

ps This is a companion article to one that lists 18 plants and flowers that you can use to repel flies and insects in your home. Check it out here:

Low Maintenance Plants that are Known to Repel Flies

Common Species of Flies Found in the US

There are some one hundred known species of flies that are commonly encountered by the average human living in North America.

There are both indoor and outdoor flies to be aware of. Some of the most commonly found species are listed below.

House Flies

House fly species usually found indoors include Common House Flies, Cluster Flies, Blow Flies Drain Flies, Fruit Flies and Lesser House Flies:

Outdoor (Garden, Patio etc.) Flies

A number of the indoor flies mentioned above can be found outdoors, such as the common house fly, fruit fly or the drain fly.

In addition, you find certain species largely outside, including Fungus Gnats, Phorid Flies, Deer Flies, Stable Flies and Soldier Flies.

Diseases Carried by Flies

As we see from the list above, most of the flies do not bite – with a few exceptions, such as the fungus gnats.

They do, however, carry all kinds of deadly diseases, due to their habit of hovering around decomposing food, animals and vegetation and visiting unsanitary locations such as drains and garbage dumps.

Some of the diseases commonly carried by flies include Dysentery, Typhoid and Cholera.

Due to the risks above, as well as the general aversion to having filth deposited on surfaces they frequent, people will throw food away if a fly alights on it. Same goes for a clean surface.

Some Precautions to be Taken

Some basic precautions should be taken to avoid a fly infestation.

Rotting food and vegetables should be safely disposed, pet food bowls kept clean, surfaces wiped down with water and vinegar, perhaps essential oils, so on and so forth.

This article is about an additional step.

The Role Played by Plants

Besides the precautions mentioned above, there exist a natural set of remedies. Many common house and garden plants (and trees) are natural insect repellents, due to strong scents that are not unpleasant for humans but hated by flies and other insects/pests.

Some go further and actually kill flies. 

Plants can be divided into normal plants (including leafy and flowery plants, grass and trees) and herbs. For this discussion, we have focused on plants only.

Common Chemicals Found in Plants That Repel Flies

One way to escape from urban legends about which plants or herbs repel flies is to do some research on some of the chemicals and compounds that are present in “natural” insecticides and repellents.

These are typically present in plants themselves (typically in flowers or leaves) or can be extracted in the form of essential oils – which can then be used to make DIY household pest eradication solutions.

The clear distinction between natural, plant-based insect repellents and many others lies in the fact that many insecticides have man-made chemicals (such as the artificially manufactured insecticide DEET).

Another group of insecticides are made from minerals that may occur naturally, such as boric powder, which may then be treated to manufacture a concentrated toxin – boric acid.

Plant based insecticides and repellents occur naturally in plants and herbs. Natural products tend to be least harmful to the environment and us.

In terms of plants, the main chemicals that repel and/or kill flies include the following:

1.  Pyrethrum

Pyrethrum is a natural substance that occurs in a variety of Chrysanthemum like plants. Its main chemically active elements – pyrethrins – are used extensively in natural pesticides.

Pyrethrins occurring naturally are less toxic than synthetic insecticides created from the same base, but it can still be toxic at high doses. People should be careful when handling it.

2.  Geraniol

Geraniol is a monoterpenoid and an alcohol. It is the main component of rose oil, palmarosa oil and citronella oil. Geraniol occurring naturally in plants can be five times as effective as citronella plants in terms of repelling flies.

3.  Linalool 

Linalool is a naturally occurring terpene found in many flowers and spice plants. It produces a pleasant smell for humans but acts as a fly repellent.

4.  Limonene and d-limonene

Oil derived from sweet oranges, sweet lemons and other citrus plants contains limonene, which is fatal to flies.

5.  Citronella

Citronella is a natural insect repellent.

Understanding the chemicals which will repel or kill flies helps in two ways – a) one can opt for plants that contain those chemicals, safe in the knowledge that they will work, and b) this knowledge also helps to understand how some of the plants, herbs or essential oils can be combined to produce more potent repellents or fly baits around the house. 

Besides the above chemicals, there are a number of plants whose odor repels flies and some which actively trap and kill flies. The list below covers a number of them. 

If you want to learn more about various insects, then checkout our site categories, we have a bunch of articles there that are totally worth reading:

Pest Category






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All the best


Steve Foster

Mad about bugs and wanting to publish as many articles as I can to help educate people about these amazing beautiful creatures! For more info check out my about page https://schoolofbugs.com/about-steve-foster/

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