8 Plants That Repel Black Flies 2023 [Plants Flies Hate]

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8 Plants That Black Flies Hate 2023 [Updated]

Simulium fly
Black flies are problematic and present in the US. There are a number of federal programs to reduce their populations. xpda, CC BY-SA 4.0, via Wikimedia Commons

There are over 2,000 species of black flies spread all across the globe. Members of the Simuliidae family, these flies are known for being especially problematic because of their chief means of obtaining sufficient nourishment. Though most male black flies feed on nectar, their widespread females suck on the blood of mammals as they prepare to lay their eggs! Many species fly over considerable distances just to access sources of fresh, warm blood, including that of humans!

Wherever thriving communities of black flies are found, they can be vectors for dangerous parasites. As they move from one host to another, they spread pathogen-borne disorders. In Africa, for example, a few species of black flies are known for spreading “river blindness”, which is caused by a parasitic worm. Black flies are also present in the US, where there are now federal programs to eliminate their populations.

Black flies tend to breed and have dense populations within the vicinity of areas with running water. Also called buffalo gnats or turkey gnats, they can compromise one’s enjoyment of outdoor activities. To protect yourself and your family from these flies, consider cultivating a garden with natural, pest-repellent properties. Many fragrant plants are equipped with compounds that are perfect for keeping pests like black flies far away!

1) Basil (Ocimum basilicum)

Potted basil
Basil is full of aromatic compounds that repel many different insects including flies, beetles, and mosquitoes. Nicole Bratt from Seattle, WA, USA, CC BY-SA 2.0, via Wikimedia Commons

Native to Africa and Asia

Now cultivated all across the globe because of its culinary importance, basil is known for its strong scent and sharp flavor. This leafy herb is chiefly grown as an annual and is usually re-grown each year to produce fresh batches of its valuable foliage. Deep green, ovate, and delicate, these are packed with phytochemicals that protect the plant. Collectively, these chemicals form a distinct essential oil.

The actual formulation of basil oil varies according to cultivar, but it is generally packed with volatile aromatic compounds. Many of these have insecticidal properties that significantly damage the nervous systems of mosquitoes, flies, beetles, thrips, and nematodes. It’s highly likely that black flies will keep their distance from dense stands of basil, especially those with freshly harvested leaves.

Yes, regularly harvesting your basil plants should consistently allow more of their oils to ooze out. The scent of these oils will naturally waft around your garden, signaling danger to many pests and potential grazers. Situate your basil plants in sunny, well-ventilated areas to encourage the production of more leaves and stems.

2) Coriander (Coriandrum sativum)

Coriander leaves
You can spread crushed, dried coriander leaves around your home or backyard to repel black flies and other insects. Thamizhpparithi Maari, CC BY-SA 3.0, via Wikimedia Commons

Native to southern Europe, West Asia, and North Africa

Also known as cilantro or dhania, coriander produces one of the most distinct, tart flavors. The taste of its leaflets is either loved or hated by people all around the world. Those that value the leaves liken their taste to that of citrus fruits. Those that simply can’t stand consuming them tend to liken their taste to soap!

Of course, a plant that receives such a wide range of sensory reactions would undoubtedly play many roles in the garden. Coriander leaves and seeds contain a complex essential oil. Its pungent or citrus-like taste is caused by the presence of terpenes and polyphenols, many of which some troublesome insects simply can’t stand. Linalool and limonene, some of the chief components of this herb’s essential oil, are toxic to flies.

When crushed, dried coriander leaves and pure extracts of its essential oil can be spread around the home or garden, it would be best to grow the herb itself. Make it a point to consistently yet sustainably harvest the leaves to release their fresh scent. The cut portions can either be used in your kitchen or combined with other herbs to create fly-repellent plant bundles.

3) Lavender (Lavandula spp.)

English lavender inflorescence
English lavender (pictured) is a popular cultivar and is known for being a natural insecticide and antimicrobial. JLPC, CC BY-SA 3.0, via Wikimedia Commons

Native to Europe, Africa, and Asia

Always a romantic addition to a cottage garden, lavender is a wise choice for its low-maintenance requirements, charming features, and relaxing scent. The tangible counterpart of the sweetest lullaby, lavender oil can serve as a weapon against the establishment of pest colonies on your property. Situate this plant’s stands in key areas of the garden, such as along the borders of your home and along entryways, for maximum effect.

The most popularly cultivated lavender species, English lavender (L. angustifolia), has thoroughly been evaluated as a botanical insecticide. With an essential oil that is rich in compounds like limonene, camphor, linalool, and pinene, it is remarkably effective at serving as a natural antimicrobial and insecticide. Organic formulations, with this oil as a vital component, can serve as an environment-friendly alternative to many chemical repellents.

Apart from directly repelling insects like black flies, the presence of lavender can discourage their growth because this plant generally prefers dry conditions. By cultivating a well-draining garden, water-loving insects are less likely to find breeding spots in bottom substrates.

4) Citronella (Cymbopogon nardus)

Citronella plant
You may need to regularly cut down or harvest citronella leaves to release their scent. Mokkie, CC BY-SA 4.0, via Wikimedia Commons

Native to tropical Asia

A member of the grass family, Poaceae, citronella has gained global popularity because of the remarkable properties of its oil. Citronella oil is widely used as an ingredient in organic insecticides and chemical-free insect repellents for children. Its properties are highly disliked by mosquitoes, various kinds of flies, lice, and even leeches.

If you’re located in the tropics, growing your own citronella plant should be fairly straightforward. It would be best to keep your specimens restricted to pots or containers of moisture-retentive soil. When given free rein in fertile soils, note that this grass has a knack for spreading quickly. In their compact form, citronella leaves are unlikely to be fragrant enough to keep insects away. You may need to consistently harvest them or cut them down to release their scent.

As an alternative, you might wish to obtain the pure form of its extracted oils and incorporate it into a homemade repellent. Spray this onto key parts of the garden, particularly in spots where pestilent insects and unwanted fungi are most likely to breed and develop. The citrus-like scent of the oil should help mask other scents that may be attractive to insects.

5) Garlic (Allium sativum)

Garlic bulbs
Garlic bulbs get their strong odor and unique flavor from a number of sulfur-based compounds. Kjokkenutstyr, CC BY-SA 4.0, via Wikimedia Commons

Native to South and Central Asia

Black flies and mosquitoes tend to stay well away from fields of garlic. While the planted form of this root crop is capable of repelling some pests, it’s the crushed bulbs, leaf sap, and extracted oils that should work best. This miracle crop is truly one-of-a-kind because its effects continue to take place even once it is eaten. Some people believe that eating a lot of garlic can make one undesirable to many bloodsucking insects!

Garlic contains a host of sulfur-based compounds. These give its bulbs their strong odor and unique flavor, which can be overpowering to the palates of many animals. Mechanically damaging the cells of the bulb actually triggers the production of potent phytochemicals. These likely function as a natural form of defense against grazers, parasites, and insects.

For the purpose of keeping black flies away, you might want to consider creating a garlic-based spray with freshly harvested bulbs (from the garden or store-bought). The bulbs should be finely chopped or mashed and added to water. Simply shake the solution, add a dash of pepper for good measure, and it should be ready for use in the garden.

6) Mint (Mentha spp.)

Peppermint plant
To repel black flies, you can cultivate a mint plant, such as peppermint (pictured), or spray its essential oil around your yard. Simon Eugster, CC BY-SA 3.0, via Wikimedia Commons

Present in all continents except Antarctica

Some of the hardiest and most rapidly-growing herbs to grace our gardens, homes, and kitchens, several mint species are fantastic additions to an insect-repellent garden. These fragrant plants are typically low-maintenance, attractive to pollinators, and highly resilient. In rich and regularly moistened environments, they can thrive as self-propagating colonies.

The most commonly grown mint hybrid, peppermint, is generally great at deterring unwanted flies. This produces an essential oil with a distinctly minty fragrance and menthol taste. Flies, which use their sense of smell to search for their next meal, tend to be taken aback by the smell of peppermint, which can mask other strong scents.

To use a plant like peppermint to repel black flies, you can either spray its essential oil or cultivate its stands in your garden. While making use of an extract can introduce a stronger or more potent smell to your yard, maintaining the actual mint plant may have more prolonged benefits. Just make sure to frequently snip off a few leaves or stems so that the scent of the oils may waft around your property.

7) Rosemary (Salvia rosmarinus)

Rosemary plants
You should harvest rosemary sprigs during spring and summer, as this is usually when black flies breed. Jane6592, CC BY-SA 4.0, via Wikimedia Commons

Native to the Mediterranean

Known for its heady aroma and its bitter taste, rosemary is a crucial component of every well-rounded herb garden. This fantastic plant, which can eventually develop into a full-fledged, evergreen shrub, is hardy and attractive. Apart from providing many ecological benefits, it can serve as a specimen plant or focal piece due to its structural features and colorful inflorescences.

The scent and taste of rosemary are produced by the mix of phytochemicals in its essential oil. Rich in camphor and several other acids, the oil helps protect the plant by fending off potential grazers and deterring many parasites and insects, including flies. Once sacred to various cultures throughout its native range, rosemary also has pharmacological uses.

If you intend to cultivate this plant to repel black flies, aim to grow it to a respectable height. Harvest a few sprigs all through spring and summer, which is usually when black flies undergo their breeding period. If you have a pond, you might want to situate potted rosemary bushes and other fragrant herbs close to its margins. Just make sure the substrate around the rosemary roots is allowed to dry out to prevent them from dying back.

8) Sweet woodruff (Galium odoratum)

Sweet woodruff in bloom
Not only does sweet woodruff add color and texture to your yard, but it is also an effective deterrent against flies and grazing animals. Jerzy Opioła, CC BY-SA 4.0, via Wikimedia Commons

Native to Europe and East Asia; naturalized in some parts of North America

Sweet woodruff is a perennial herb that grows best in partly to fully shaded areas. If you find that your shade garden is frequented by insects, you should try adding in a few well-established clumps of this fragrant species. Apart from adding color and interesting texture to a space, it should flourish as a ground cover plant and serve as an effective deterrent against flies and grazers.

Once used as an additive to increase the sweetness of syrups and juicy drinks, sweet woodruff contains an aromatic compound called ‘coumarin’. Now found to be quite dangerous in high doses, having shown a toxicity potential in studies with rats and mice, coumarin can no longer be used for industrial purposes.

It’s highly likely that, although the sweet smell of this herb appeals to us humans, its high concentration of coumarin staves off its grazers and pests. Sweet woodruff is thus perceived as a natural fly repellent. Try spreading potted clumps of this species around shaded parts of the garden and patio. This should increase the reach of its vanilla-like scent.

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