How to outwit the mosquito

Alex Watkins has a look at sprays, burning coils, bracelets, plug-ins and some home-made products used to keep the dreaded mozzies at bay

“THE MOSQUITO’S a clever little bastard. You can track him for days and days until you really get to know him like a friend. He knows you're there, and you know he's there. It’s a game of wits. You hate him, then you respect him, then you kill him.”

These were the words of the intrepid mosquito hunters in Monty Python, who proceeded to use a bazooka and a machine gun to kill their prey before skinning it as a trophy.

This may seem rather extreme and impractical but finding effective protection against mosquitos can be expensive and frustrating so to save time, money and further discomfort, it is worth analysing the science behind them.

Much like many cosmetic products that promise to make us look younger or thinner, there is an awful lot of marketing out their designed to make us buy certain products which may not be the best choice.

This is demonstrated by the results of a survey by Spectrum Brands in areas at risk of the Zika virus and other diseases transmitted by insects.

One might think people would be more clued up when faced with these risks but they found that only 20% of people used mosquito repellents and, more shockingly, that 82% of them used products that are not effective at all - ignorance fuelled by disinformation Moreover, we can all testify to having experienced how mosquitos tend to pick on some people more than others, further proof that life is just not fair.

One factor that determines this is body odour and temperature – that is to say hot bods get stung more. Hormones and cosmetics can also make a difference.

Some of us also react more severely to insect stings than others, which is determined by our immune system response (although conversely the more we get bitten the less severe the reactions should be).

Human beings excrete lactic acid and octenol through the skin and produce carbon dioxide when we breathe, all of which attract mosquitos.

As a result most repellents camouflage us by disorientating the insects so that they cannot find us, but cannot stop them biting us if they happen to land on us.

It is worth noting that mosquitos do not navigate using sound and so high-frequency noise-based repellents have no proven efficacy (but can annoy dogs and small children).

When choosing a repellent that is applied to the skin or clothes, there are certain ingredients to look for: diethyltoluamide (DEET), which is a true repellent, along with eucalyptol, linalool, and thujone.

A DEET concentration of 30% should be sufficient in this part of the world ,which should last 3-6 hours, although higher concentrations last longer. Nothing stronger than 30% should be used on children and it should not be used on babies.

It has been subjected to very extensive testing and can be considered safe, although some people can suffer skin reactions (high concentrations can dissolve some plastics) and it should not be used on damaged skin. Icaridin has been found to be as effective if not more so than DEET at a concentration of 20% and is used in several commercial products, although not all are the same strength.

Repellents applied to the skin should be applied after sun screen otherwise they will be masked, although sun screen needs to be reapplied every two hours and chemical repellents should not be used so often.

Plug-in repellents usually use the insecticide prallethrin and can be effective indoors so are commonly used at night, however it is worth noting that the dreaded tiger mosquito is a creature of the day.

Despite many claims that eating vitamin B supplements repels mosquitos, this has not been proven and is not advisable unless we have a deficit of it.

Bracelets appear in displays at pharmacies every summer and can seem like an unobtrusive or even attractive option but most only use citronella and this only really has an effect in the area immediately surrounding the bracelet itself.

Citronella, an oil extracted from lemongrass, is one of the most well-known natural repellents but has been found to raise the heart rate of some people and was actually banned as an active ingredient in any insect repellent under EU legislation in 2006, although not for use in perfumes – which is why you can buy citronella body spray.

Its effectiveness in candles depends largely on the prevailing wind, a problem that also affects the slow-burning coils which also contain chemical ingredients, which makes them generally more effective.

However they produce a lot of smoke so should not be used inside (even though it is not regarded as toxic), and care should be taken over the risk of fire when used outside.

Also tiger mosquitos fly close to the ground so are unlikely to be put off by smoke rising from a table.

Lemon eucalyptus essential oil, also known as menthoglycol, has been shown to be one of the most effective natural mosquito repellents, performing as well as DEET in studies.

So, don’t be fooled by packaging or the latest hype, check the ingredients to see which are most effective and safe products to use, depending on the circumstances, and follow the instructions.