Plants that kill mosquitoes: the repellents that we will not find in the pharmacy, but in nature

Summer: that season as beloved as sometimes feared. As temperatures rise, so do the inches of exposed skin and attractions that are not always welcome are turned on. Winged suitors of invasive kissing appear, as spicy as it is annoying, and that can border on bullying for the unfortunate victims whose blood is especially sweet to their taste. Mosquito love: no, thank you (and even less for those who live in places where the kiss of these insects is not only an uncomfortable itch but also a potential health risk, since they are vectors of malaria, sleeping sickness, encephalitis and other microbial niceties) .

In summer the annoying enemy returns and we go down to the trenches, arming ourselves with any remedy that helps to combat it. In love and war, they say, anything is allowed…or was, at least: after decades of relying entirely on lab-invented concoctions, more and more people are seeking weapons repellents that have not come from a test tube but from a plant.

But is all that glitters gold in the wonderful world of citronella and company? Before starting the skirmish, it is convenient to inform yourself well on the ground.

Mosquitoes and remedies: preliminary dossier

The first thing that should be clarified is that, alas, for now and as far as is known, the universal anti-mosquito plant does not exist.

To begin with, more than 3,500 species of insects are hidden behind the term mosquito, and each place has its own (and, now, also some that have come from afar, such as the Asian tiger mosquito, Aedes albopictus, that has been installed in many areas of the planet). Each species has its habits, tastes and preferences; For example, in Spain, the common mosquitoes of a lifetime (Culex pipiens) are mostly nocturnal, but winged tigers are very active during the day. This variability also extends to the world of mosquito repellents; hence a plant that is unpleasant to one species need not be so to another. The only way to know for sure is to try it.

Our anti-mosquito arsenal is made up of two corpus different: on the one hand, the traditional knowledge of the grandmothers; on the other, the scientific studies that have tried to determine and quantify, under controlled conditions, the effects of certain plants on this or that species of mosquito. Since many traditional remedies have not yet been the subject of scientific study, there is still no concrete data to support or deny their effects.

These effects are of different types (a repellent, which drives away the suitor, is not the same as an insecticide, which leaves it dry on the ground) and even vary depending on how we use the same plant. It is not the same that it is sown and fresh in a pot than having a dry twig hanging on the wall, burning the leaves as if it were incense or extracting an essential oil to apply it to the skin (just as it is not the same to have an orange tree in the garden, drink an orange juice or put on a perfume with neroli).

Armed with these basics to tackle the vast literature on natural mosquito repellents without getting riddled with it, let’s see how plants can help you avoid the attentions of the most common European mosquitoes.

First line of defense: the garden of heartbreak

Creating an environment full of plants whose mere presence is disliked by mosquitoes is always a good idea; among the species with proven results, our old friends the basils stand out, of course (ocimum sp.). Having pots of basil full of pots—or at least some near the windows—is a good start to discourage potential stalkers. However, the effect of any plant sown has a limited radius of action: since its repellent power depends on a series of aromatic compounds that it releases into the air around it, if you move too far away, your protection disappears. Hence, it was a peasant custom to walk with an aromatic bud behind the ear, or near areas of exposed skin: to have a “portable” protection that traveled with one.

Among the species whose volatile compounds do not please several mosquitoes are, for example, thyme (thymus vulgaris), various mints (mentha arvensis, m. x piperite), rue or certain eucalyptus trees. And if we approach plants, distiller in hand, we will obtain a wide repertoire of plant concentrates to spread in the air or spread on the skin, and that today everyone wants to enlist in battle: essential oils.

Second line of defense: essential, oily, repellent

There are, yes, essential oils that offer proven protection against various mosquito bites, keeping them at bay; it is even possible to prepare a synergy, a combination of oils that work better together than separately to scare away those awkward friends. Among the plants whose oils pass with flying colors in the studies, citronellas stand out as good friends (different species of the genus cymbopogonas C.nardus) or lemon eucalyptus (Corymbia citriodora), as well as certain geraniums (eg. pelargonium asperum) or species of the cinnamon genus (cinnamomum sp.).

Until now the good news; now comes the small print of the instruction booklet, which should be read carefully.

Essential oils are made up of volatile compounds (which is why they are aromatic: odorous molecules volatilize and reach our noses), and this means that the protection they offer is temporary: in most cases the effect literally evaporates. in a matter of half an hour. That is why many commercial formulas that include, for example, citronella oil in their composition strive to stabilize it, combining it with other compounds such as vanillin, and prolonging the active protection for up to two hours.

By the way, they are called oils because they are oily to the touch, but their similarities end there: chemically, an essential oil of, for example, geranium, has nothing to do with olive oil. Edible fatty oils can be extracted from olives, almonds, sunflowers or soybeans, many of them moisturizing for the skin. Essential oils, on the other hand, are usually obtained by distillation, they are volatile, aromatic, and biochemically active: they contain an endless number of different compounds that plants use to defend themselves from herbivores, attract pollinators or dispersers… These concentrates have many therapeutic properties interesting for humans, but depending on the dose and the method of use, they can be toxic, so it is essential to use them correctly.

For all this, be careful: these plant chemicals (after all, plants are the great inventors of chemistry and pharmacy) do not have to be, in themselves, sustainable or safe. There are essential oils that should not be applied directly to the skin because they can cause allergies, photosensitivity in contact with sunlight, problems during pregnancy… No matter how effective clove oil may be (Syzygium aromaticum) against mosquitoes in laboratory tests, its direct application on the skin is strongly discouraged, as is its use during pregnancy or in young children. Therefore, if you want to use these compounds in battle, you should be very clear about the contraindications and precautions recommended in each specific case and consult an expert opinion. Very sensitive skin will always have the possibility of vaporizing these aromas in a diffuser, and dressing in light tones, less attractive to mosquitoes. And, when it is too late, a drop of lavender essential oil (Lavandula latifolia) will help calm inflammation. Plant solutions may not be infallible or universal, but, well used, they can be great allies in the hard fight against mosquitoes.