MOSQUITOES: true and false in twenty answers
Does eating garlic keep mosquitoes away? Who has "sweet" blood gets stung more? Can you get bad diseases from a mosquito bite? The questions (and urban legends) about buzzing insects are many: we answer the most frequent doubts with the help of some experts from the Department of Agricultural Sciences of the University of Bologna, and the Dermatology unit of the Humanitas Clinical Institute of Rozzano (Milan).
Why do they only sting females?
The female mosquito needs a blood meal to mature its eggs; the male feeds on sugary substances found in nature. The female bites for the first time after a few days from its formation, following the metamorphosis.
How many times do they strike?
The mosquito lives from three to five weeks, during which it produces as many cycles of eggs: it therefore bites three to five times in all.
Why do some attack during the day?
Behavior is part of the intrinsic characteristics of each species (it is estimated that there are about 2700); for example, the tiger mosquito also bites during the day, while the common mosquito only bites in the evening.
How much blood do they suck?
The female usually takes about 2-3 milligrams of blood approximately equal to her weight.
Does the "tiger" even pierce the clothes?
Many species manage to do this. The honeycomb cotton of summer polo shirts is easily overrun by mosquitoes.
How far do they go from the "nest"?
The mosquito lays its eggs in places suitable for the development of the larvae, or in more or less natural, small or large water collections, called "foci". The ability to move away from the outbreak and dispersal in the surrounding areas changes according to the species: some mosquitoes remain within a few hundred meters, others fly up to 10-20 kilometers away from the outbreak.
Why do they emit the typical buzz?
The annoying noise is caused by the very fast flapping of the wings; it is an insect that can fly very fast, covering up to three kilometers in an hour.
Where do they like to hunt?
Each species has its own food preferences, so not all mosquitoes "love" the animals they would find in the countryside. The tiger mosquito, the most common in our cities, prefers to feed on humans; a research from the La Sapienza University of Rome has shown that human blood is found in 75% of "city" mosquitoes, against 60% in "countryside" insects.
Why do they make us scratch?
While biting, the female introduces saliva into the host, which contains anticoagulant substances to counteract the defenses of the prey and ensure a good blood supply. It is the saliva that is irritating and determines a more or less marked response depending on the subject.
Are there hyper-sensitive people?
Yes, and in those who are allergic the reaction to the sting is excessive, the wheal is immediate, with erythema and sometimes even lymphedema (swelling from accumulation of lymph); in some cases raised and hard papules are formed that can last up to a few days. The allergy tends to resolve over time in most cases, but there are adults who continue to have a hyper-reactivity to the mosquito. Normally, however, the itching appears immediately and lasts about half an hour, so you have the "bubble" which, however, is small and disappears quickly.
Can they be a vehicle for viruses?
Yes it is possible (malaria is spread precisely by mosquitoes, in countries where it is endemic), the recently discovered Zika virus and it has also happened with the Chikungunya virus, of which there has been a small outbreak in Romagna.
Why do defenses often fail?
In addition to the natural loss of effectiveness of these products over time, repellents interact with the skin and its odors: this means that on some people the repellents may not work well, on others they may not even serve at all to keep mosquitoes away. Repellents based on natural substances (Neem oil, Citronella, Geranium) in the end proved to be the most effective, without being harmful.
Is there anything that attracts them?
The odors emanating from our body and the carbon dioxide we produce by breathing are the main factors that make a person more or less "palatable" for the mosquito's meal.
Are there anti-mosquito foods?
Yes, if they affect our smell. Garlic, for example, modifies it, but there is no scientific evidence that it can keep mosquitoes away.
Are perfumes counterproductive?
Those used in cosmetics, such as aftershaves or real perfumes, do not attract mosquitoes; on the contrary, if they mask body odors they can even act as repellents. However, in the interaction with the skin, the aroma can change and have different effects.
Does blood group affect?
The blood type does not matter, but there are indeed people who are bitten more frequently, due to the specific mix of odors they emanate.
Are those who sweat a lot more stung?
Those who sweat a lot emit more odors and more water vapor, making them more "attractive" to mosquitoes. High body temperature also attracts the insect. It is no coincidence that the mosquito that spreads malaria bites people with fever, when the protozoan causing the disease is at its most present in the blood.
Does turning off the lights protect us?
Mosquitoes do not have very developed eyesight, but they perceive light and heat and are attracted to them.
What "function" do mosquitoes have?
Mosquitoes are also part of the balance of the ecosystem: the larvae feed aquatic animals and "clean" the water of organic substances and bacteria, the "adults" are food for bats and birds.
Why are they there even though it's not hot?
Especially the tiger mosquito, more resistant to low temperatures, can be present even beyond spring-summer.