What is a natural mosquito repellent?

When launching our own natural mosquito repellent, Canelle Spray, we researched the mosquito repellent market carefully to see where we would fit in.  We were surprised by what we discovered and we’d like to share this with you now. 


The way mosquito repellents generally work is that they mask the chemical clues that mosquitos use to find you. In all mosquito repellents there is an “active ingredient”, which is what achieves this effect. Active ingredients in mosquito repellents are classified by the Environmental Protection Agency in the US as either chemical pesticides or biochemical pesticides. 

Chemical pesticides are just a mix of chemicals. DEET is the best-known and it’s unashamed of its chemical pedigree. It's long established and proven effective but smells awful and burns plastic. After many decades of use it’s considered relatively safe by most public health authorities but it has a bad rap.

Biochemical pesticides (which they go on to refer to as “biopesticides”) are derived from plants, says the EPA. You’d have thought that the classification would be straightforward: DEET is a lab-mix of chemicals while citronella oil, for example, is an essential oil distilled from the lemongrass plant. But unfortunately the phrase “derived from plants” allows a lot of ambiguity. In fact it’s become so problematical that the EPA has formed a special committee to decide whether a pesticide should be categorised as ‘chemical’ or 'bio'. And there’s a lot to go for: it seems to be generally accepted that if your product achieves the ‘bio' prefix you can distinguish it as a natural product.

So what’s the controversy about?


Plant oils are natural substances that come from various parts of a plant and are extracted by means of a simple process of steam distillation. However each of these plant oils is actually made up of a complex mixture of naturally occurring chemicals and it’s now possible to replicate some of these chemicals in a lab. If you can identify which chemicals have the mosquito repellent effect you can replicate the necessary compound and use it as your active ingredient.  

The EPA classifies these chemical ingredients as biopesticides on the grounds that: 
1. The basic molecular structure is very similar to the natural ingredient. 
2. The functionality - that it repels mosquitos - is also similar.
3. The product is non-toxic, biopesticdes are non-toxic, therefore the product is a biopesticide (a manifestly false argument but there we are). 
In other words, if it looks like a duck, walks like a duck and quacks like a duck, it’s probably a duck. Put like that, it seems fair enough.

Where’s the problem?  


The problem is that when consumers look for a natural product they have in mind a product that has as its base some sort of naturally occurring substance. But these are Frankenstein ingredients. Take PMD for example, which is the active ingredient in many well-known mosquito repellents (it’s often labelled in the small print as Citrepel 75 in the US and as Citriodiol in the EU). It so happens that PMD is present in minuscule amounts in the essential oil of the eucalyptus tree. Chemists take the oil and do something that "mimics and accelerates the ageing process” (I quote from the manufacturer) to increase the amount of PMD. Put another way, they make the PMD grow bigger and older, very quickly, in the lab. It sounds pretty creepy and it’s certainly not natural. The EU regulatory authorities allow this process to be described as "cyclized" (?!). Manufacturers sometimes describe these synthetic products as "botanical” but the technical term, which manufacturers avoid, is “botanical replicant” which certainly captures the weirdness of the product.  


To add to the PMD picture, marketing people have been allowed to refer to PMD (proper name paramenthane-3, 8-diol) as “oil of lemon eucalyptus” and it’s often mixed with genuine oil of eucalyptus to reinforce this disguise. They then add other (plainly unnatural) chemical ingredients to make the products easier to prepare or apply.


But actually this product is hardly different from DEET. It’s just that the chemically synthesised active ingredient resembles something that, by fortunate coincidence, can also be found in tiny amounts in a plant. But the manufacturers even refer to “PMD rich botanical oil” as though this chemical ingredient were making the product even more natural.


Other common examples are IR3535 which is made to replicate a naturally occurring amino acid and Picaridin which is made to resemble a natural compound pipeline found in the black pepper plant. Even citronella oil, which can easily be extracted as a natural oil from lemongrass, is commonly synthetically replicated in a lab instead because the process is cheaper. And they all smell horrible.



How far does the ‘natural’ disguise go?


It’s alarming to see how the marketing people commonly shuffle the words and stretch the meanings. Here’s how it goes.


First off, put it about that consumers should only consider insect repellents that are registered with the EPA because, without this, the products are most likely ineffective as well as toxic. This has become a very common misunderstanding. In fact, EPA registration says and implies nothing about the effectiveness of the product as a mosquito repellent; it merely considers the human health and environmental effects. Furthermore, the EPA has listed 21 truly natural insect repellent products and specifically exempted them from registration because they have been assessed as minimum risk. Put another way, products that have been registered with the EPA are those that one might otherwise suspect to be toxic.


Next, use weaselly words like “of vegetable origin”, “botanical" and "plant-derived", mirroring the EPA starting point. Another term is “originated as an extract of….” Or just make up a word: "biocide" has been adopted by the European Union regulatory authoriities - it's a uncomfortably close to "suicide" but the bio prefix is obviously thought to be worth it in marketoing terms. Whenever you have to use scarey chemical words, mark them with asterisk and then explain that these are “natural components...expertly controlled… with patented technology”. Then summarise the whole package artfully as "nature's repellent, backed by science."


Next, suggest that the product contains "natural active ingredients", then that it contains "natural actives” (remember that natural things aren’t meant to have ingredients), then that it contains "natural substances" (much better word than actives) and finally declare that the product itself is natural. It’s like the game of grandmother’s footsteps: a tiny step at a time and she won’t notice.


Try the bait and switch: “we use natural active ingredients” morphs into “we only use natural active ingredients”. What about all the inactive ingredients? How natural are they?


Blind with science: ““patented slow-release technology…reduces the active’s penetration into the epidermis” meaning that they add something to make the repellent stay on your skin rather than evaporate naturally. Are you happy with that?


Make sure that, alongside the active ingredient, there are some genuinely natural ingredients. Then you can say that the product is "packed full of natural ingredients” and finally be sure to add “…all blended in a unique process."


Next, target the competition and define youself by what you’re not: say something like “DEET and Picaridin-free formula (no synthetics)” - I quote from the labelling of a PMD product.


Next, claim a stamp of approval. Many local health authorities recommend the use of insect repellents containing any one of the four most common synthetic active ingredients (DEET, PMD, Picaridin and IR3535). Following this, manufacturers claim that their particular product is “…approved by...” the health authority. Better still, get one of those “natural” certifications. It’s easy. Often  the certification includes: "...no controversial chemicals....”. How comforting is that!


And finally, once you’re all set up with a marketing name, go on to Lonely Planet or Trip Advisor, plant a question such as “I’ve heard of a new natural mosquito repellent called xx. Has anyone tried it?” and then let the bots do their work. It’s easy to recognise the same people making the same comments, often verbatim, on the threads.  



Which leaves us with natural (non-synthetic) plant oils


Of course we have an interest here: our own insect repellent, Canelle Spray, is made from the essential oil of cinnamon leaves and bark, remixed with the water left over from the steam-distillation process; and nothing else. The oil extraction is an entirely self-sustaining process as we use yesterday’s spent leaves and bark as fuel for today’s distillation. It’s what you might, in this context, call super-natural.  

Does it work? Yes. It’s 97% effective according to the London School of Hygiene & Tropical Medicine but, like PMD, it doesn’t last as long as DEET. It can sting a bit at the start, like IR3535, but it smells lovely. Unlike any of the synthesised biochemical products, it’s true to nature. You could make it in your garage. And how does it compare with other natural plant oils? It works.

For a genuinely natural mosquito repellent that works, there’s only one choice.

PS August 2020 a new synthetic chemical ingredient with insecticide properties has hit the market.  It's called Nootkatone and it mimics a natural substance found in the Alaskan yellow cedar tree, cupressus nootkatensis, which "is derived from the language of the Nuu-Chah-Nulth people of Canada (formerly referred to as the Nootka people)".  Don'tcha love it?  Bonuses all round in the marketing department!