Forget candles and bracelets: what works and what doesn't against mosquitoes

With the mosquito season already underway, we give you the keys to understand how and why they bite and how to combat them

5 min
The common mosquito

BarcelonaSummer and mosquitoes go hand in hand and getting bitten is practically inevitable. Although bites are not serious, they are usually very annoying, and prevention, as always, is key. However, it is important to be aware that most remedies against mosquitoes are not all that effective.

Entomologist Rosario Melero-Alcíbar, a doctor in tropical medicine, parasitology and biological sciences, has been studying mosquitoes for almost 30 years. She explains that it is difficult to determine when the mosquito season begins, since it depends on "temperatures, especially at night, and the presence of water. This will determine whether it starts earlier or later". She adds, however, that in the case of the common mosquito "it is less restrictive in terms of temperature, since it can take advantage of any environmental conditions. This can make it appear earlier and disappear later".

The specialist in sanitary entomology points out that "when it is very hot, like it has been these last few days, its appearance is accelerated, despite the fact that we must bear in mind that it is essential that there is also water for the larvae to grow, otherwise there will be no mosquitoes". This is why Rosario Melero-Alcíbar insists on a key point in preventing the appearance of mosquitoes: avoiding the presence of standing water. "In areas where there are tiger mosquitoes, which in Catalonia are very present, it is very important to control the watering of plants to prevent water from accumulating in saucers". We also have to avoid the presence of other containers where rainwater can accumulate, because they are the space that mosquitoes look for to lay their eggs. Small concentrations of dirty water are their ideal habitat. As for the common mosquito, the one that usually enters the house at night, the entomologist warns that "it has very wide trophic preferences, so that it does not matter whether it breeds in an abandoned swimming pool or in a hole in a tree". Although there is drought this year, this does not necessarily mean fewer mosquitoes. As Rosario Melero-Alcíbar explains, "a lot of heat with little water ought to mean fewer mosquitoes, but then it is us who provide the water; that's why we have to be so vigilant".


The first tip to reduce the presence of mosquitoes is clear: reduce the presence of standing water. Apart from that, the entomologist recommends the use of mosquito nets, pointing out some differences regarding the behaviour of common and tiger mosquitoes. "Tiger mosquitoes do not usually enter homes and bite throughout the day, while common mosquitoes take advantage of the night and enter homes; therefore, putting up mosquito nets on windows can help us". Melero-Alcíbar explains that each species decides when, how and where it bites each person according to conditions such as air, temperature, oxygen conditions, etc., and "once it has bitten us, it leaves to rest and metabolise the blood it has taken from us. And they can do this by hiding in a tree, for example".

As for the whole string of products on the market that promise to put an end to mosquitoes, the entomologist warns that few of them are of any real use. In her opinion, the most effective are repellents we put on our skin. "And make sure it's well applied. They will approach us, but they won't like the smell and will leave. As for citronella candles, bracelets or insecticides plugged into sockets, the truth is that they may confuse them a little, but they won't be enough. We would have to be surrounded by these remedies for them to be minimally effective". Regarding the use of repellents, Melero-Alcíbar says they must be re-applied regularly and, if using suncream, we must first apply the suncream and then put on the repellent about 20 minutes later. "And if we get wet or sweat, we have to repeat the operation to ensure it is effective.


It is female mosquitoes that bite, as they need our blood, or that of other animals, to reproduce. "Mosquitoes, generally speaking, both males and females, get their vital energy from the carbohydrates they can get from flowers, and females seek the blood of different hosts to get the fats and proteins they need to develop their reproductive apparatus and lay good eggs." The entomologists calls them "supermummies", explaining they look for the best food to fulfil their reproductive mission and lay as many eggs as possible. And, in this sense, it must be said that the common mosquito, for example, likes the bird blood especially, "although if they have a human closer by they may choose them", since the goal is to get the food they need to lay eggs. Their maxim, as the specialist in sanitary entomology points out, is "maximum performance with minimum effort". "That is why tiger mosquitoes bite us on our legs, since they are normally more exposed, while common mosquitoes bites us at night, when it can choose other areas, taking advantage of the fact that while we sleep we are more relaxed and it is easier for them".

How should we treat mosquito bites?

The bites appear after the mosquito pierces our skin to get the blood. It is a skin reaction that causes itching and discomfort and generally disappears on its own after a few days. In some cases, however, they can cause swelling, pain and irritation. For their treatment, there are all kinds of recommendations and remedies, both medical and home remedies.

Dr Fernando Méndez de Paz, allergist at AMiQ (Agrupació Mèdica i Quirúrgica), points out that stings can cause a greater reaction in some people than in others due to "a sensitivity problem". "If a person is more sensitive to the urticarial substances that the mosquito injects when it bites us, then a somewhat greater allergic reaction is produced". However, Dr Méndez points out there is no need to be afraid of mosquito bites, since although they can be very annoying, "they are not dangerous and are never lethal. Some of the substances they inject can be allergenic, but they are not poison as is the case of wasps and bees, which can cause more serious reactions". According to the allergist, the most serious problem in relation to mosquito bites can be that we generate an infection in the area if we scratch the bite.

Dr Méndez also wants to reassure parents of children with very strong reactions to bites and who are afraid of how they would react to bee or wasp stings. "The symptoms have nothing to do with mosquito bites. A big reaction to mosquito bites does not mean in any case that they are allergic to wasp or bee stings; there is no relation. Therefore, it is not necessary to carry out an allergy study due to the fact that there are severe reactions to mosquito bites".

Having clarified this point, when a mosquito bites us, Dr Méndez recommends washing the area with soap and water to avoid possible infections; apply local cold with ice wrapped in a cloth or towel, avoiding direct contact with the skin to anaesthetise the area a little and reduce the discomfort; if necessary, apply a cream with corticoid or with corticoid associated with antibiotic; and if the itching is very annoying, take an oral antihistamine. If this does not improve, you can go to a health centre to assess whether it would be necessary to use oral corticosteroids.

Disproving urban myths

Does bright-coloured clothing attract more mosquitoes? The truth is that they are more attracted to dark clothes, and it is likely that if we wear patterned clothes they will approach us more because they can confuse us with the colours of flowers.

Are they attracted by sweat? Each of us has our own smell that we do not know how to distinguish them, but animals do. Our smell has certain chemical markers that attract them more or less, and if we sweat these can become more intense.

Does drinking alcohol mean you get bitten more? This is true, since we metabolise excess alcohol and expel more CO₂ through our skin, which attracts mosquitoes

Does being overweight mean you get bitten more? Also true, because we are more likely to sweat more and emit more CO₂.

Tips on how to apply mosquito repellent properly

- Apply it as many times as the manufacturer recommends to ensure effectiveness. The protection lasts a maximum of a few hours.

- Apply it outdoors or in well ventilated areas.

- Do not use with children under 2 years of age. In older children, supervise application.

- Wash hands thoroughly after application.

- Do not apply on the face or where there is a wound.

- It must be applied directly on the skin. It will not be effective on clothing.

- If sunscreen is used, leave a time interval between applications.