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Mosquitoes and other stinging and biting insects may figure in your six weeks in Alaska! Mosquitoes in Alaska will not give you Malaria, but their bite can become infected and they can be most annoying! You will be issued (it is hoped) with DEET (Diethyltoluamide) purchased locally – check that you do not react to it before you go to AK. Prevention is always better, mosquitoes don't particularly like the sun and they are especially active early morning and late evening. To lessen their effect:
Wear light coloured clothing – certain colours are said to attract?
Cover up with trousers and long sleeves (and a mosquito net?)
Check that all mosquitoes have "left" your tent before sealing it for the night.
A recent newspaper article may offer you interesting reading.
"The worst part of the mosquito experience is the anticipation of the attack. People who are old enough to remember the Second World War compare it to the approach of a German V-2 rocket. You would be lying in bed and hear a noise like that of a motorcycle engine getting louder and louder in the sky. Then the noise would suddenly stop. You would know then that the bomb had started its descent, but you wouldn't know where it was going to explode. All you could do was bury your head under the pillow and pray.
It is much the same with mosquitoes – the same tension, the same terror, the same helplessness. On the first night of your Mediterranean holiday (!) you go happy to bed, intoxicated by the scent of orange blossom, the chirruping of crickets and the sweet singing of nightingales. You are drifting contentedly into
unconsciousness when the buzzing begins. It is a hideous whining noise, full of resentment and aggression. It is the buzzing of a creature preparing to feast on your blood but only after a ritual war dance designed to intimidate you. The buzzing rises and falls. You can never quite tell where it is coming from. Then it stops. This is a moment of pure panic. You know that the mosquito has landed but you don't know where. A moment later, you do. You can feel it on your ear. You slap your ear frantically, but its too late. The brute has sucked your blood and gone.
Mosquitoes can sap the morale of even the most irrepressible holidaymaker. They are torturers of the most sophisticated kind, subtle in their choice of victims and of points on the body to strike. Those most lacking in confidence in their appearance on the beach are singled out for the greatest disfigurement. Those of the greatest modesty will be bitten in the most private and embarrassing places. The most conceited and objectionable people, on the other hand, may be left completely unmolested. There is no justice or decency in a mosquito's make-up.
Unfortunately, there is no completely satisfactory way of taking on the enemy. Few triumphs in life are more pleasurable than squashing a mosquito, but it is a pleasure which comes seldom and to few. And after you have been bitten, there is no way of taking revenge. You can, of course, rub on some sickly – smelling lotion to stop you yearning to scratch your bites. But this can only alleviate the discomfort – not the humiliation.
No, you must take stringent precautions in advance, arming yourself with weapons of defence. Do not, however, expect them to be totally effective. The instructions for Mosqui-Go Wipes, tissues soaked in a liquid mosquito repellent, say you should " spread moisture from the wipes evenly over the areas of skin you wish to protect" – as if there could be any areas of skin you did not wish to protect. A body spray might be better, but you are advised even with that to avoid contact with eyes, nose and mouth – thus leaving the mosquito some tempting little openings, which it will undoubtedly exploit.
At night, you can light those slow-burning coils that give off smoke which is noxious to mosquitoes, but which may smell quite unpleasant to you as well. Probably the most effective deterrent is the mosquito net, which also has a certain old-fashioned romance about it. Although you may feel you are suffocating in hot weather, it remains the most dignified response to those vile and persistent little insects which, in all their 2,500 varieties dedicate their mercifully brief lives – usually no longer than a fortnight – to the persecution of humankind.
There is only one thing worse than being savaged all night by mosquitoes: your companion announcing the next morning that they haven't been bitten at all. The question of why mosquitoes prefer some people to others has been baffling entomologists for many years. No one has come up with an answer yet, but experts are pursuing two lines of enquiry. First, mosquitoes seem to be attracted to an appetising cocktail of chemicals produced by humans in varying amounts, depending on their metabolic rate. And secondly, some people's reaction to bites is mild, creating an impression, perhaps, that they haven't been bitten at all.
Although a mosquito's behaviour appears to be vindictive, it bites humans simply because it needs the protein in our blood to make eggs. Only the adult female troubles us, but it is capable of generating 200 eggs every three days, requiring a full feed of blood each time. In Europe, there are literally hundreds of species of mosquito. Among the most annoying in Britain during the summer are Anopheles atroparvus (which carries malaria in the tropics, and bites in the early evening and just before dawn), the molestus form of culex pipiens (which also attacks humans in winter) and Aedes detritus (which feeds in the daytime). Aedes detritus exists along coastlines and has probably ruined more seaside holidays than any other species. "They are voracious human biters", says Nigel Hill, head technologist at the London School of Hygiene and Tropical Medicine. "They are very domesticated and have a thirst for human blood".
Ominously, mosquitoes can detect their quarry from up to a quarter of a mile away. Imagine two people sitting outside a restaurant on a balmy summer's evening. Four hundred yards downwind, chemo-receptors on the antennae of a female mosquito respond to an " odour plume" emanating from the humans. The mosquito is instantly attracted and flies upwind on a diagonal trajectory. The moment it passes out of the plume, it turns and heads the other way, thus zigzagging ever closer towards its target. Once the mosquito gets to within two or three metres, it searches for close range behavioural clues, which will reveal detailed information about its potential host. At this point, it will either turn away, or fly in to land on one or other of the humans. The question is: who will it choose, and why?
"The chemicals that attract mosquitoes are given off by everybody ", Hill explains. "We know which ones they like, but there is something about the ratio between them that makes some people more attractive then others. It's very baffling".
The initial odour plume consists of carbon dioxide and a range of chemicals found in human breath, sweat and excreta. We produce up to 400 of these as by-products of our body metabolism, and most of them are released through the skin. At close range, a mosquito homes in on the sweat components – principally, lactic acid and carbon dioxide – and will find them even more attractive if the skin is warm. (convection currents are set up around the surface, carrying the chemicals out from the body.) We can't do much about these by- products – they appear to be linked to diet, health and exercise – but scientists are working hard to solve the riddle of precisely which chemicals, and in what combination, prove more attractive than others.
In 1995, Bart Knols, a research student at Wageningen Agricultural University in Holland, nobly sat in his underpants inside a mosquito net hoping to establish that few things are more irresistible to a mosquito than smelly feet. He released a batch of Anopheles mosquitoes one at a time and found that 75 % of them headed straight for his feet. (Anopheles is the only genus that prefers biting the feet and ankles. Most choose the face, probably because of the concentration of carbon dioxide, and hands.)
He then washed his feet with disinfectant soap and repeated the experiment. He was still attacked, but they did stop going for his feet. The mosquitoes were then tempted with a lump of Limburger cheese, which
has an almost identical odour to smelly socks. A piece was placed in a wind tunnel and the insects were duly drawn to air that had passed over it.
The experiment was groundbreaking, proving that mosquitoes are attracted to fatty acids in Limburger cheese and unwashed feet (both produced by similar bacteria). But it didn't stop anyone being bitten. Given the choice of ripe feet or a hand, mosquitoes will go for the feet, but if the feet are clean, they will bite the hand. Similarly, if two people are in a room and person A is bitten 30 times and person B is not bitten at all, person B will be attacked if person A leaves the room. "It's always a relative thing with mosquitoes", says Hill. "We are a long way from recreating the complete attraction of a human. The whole effect appears to be greater than the sum of its chemical parts."
If proof were needed of just how choosy mosquitoes can be, Hill's colleague at the London School of Hygiene and Tropical Medicine, Professor Chris Curtis, carried out an unprecedented experiment in 1985 involving four locals in Tanzania. Over a period of 72 nights, Mr A, B, C and Mrs. D valiantly bared their legs for three hours each evening and counted the number of times they were bitten by Anopheles and Culex mosquitoes. The findings showed not only that individual members of the team had different levels of attractiveness, but that certain species preferred some people to others. "There was a clear person-species inter- reaction," says Professor Curtis.
He is, however, keen to point out that humans can react very differently to mosquito saliva when they are bitten. (The saliva, inserted into the skin through the hypo-pharynx, contains an anticoagulant to stop the blood from clotting and causing the surrounding area to swell). "I sometimes wake up in the night, feel a few itches and by the morning they're all gone", he says. "Other people react violently and their bites can itch for days. This is one of the reasons people often say, 'I am always bitten, but my husband is not.' It is an allergic reaction to the salvia."
Dr. Alison Blackwell at the Department of biology, Dundee University, also stresses that people's immune responses vary considerably, and this in turn affects their reaction to bites. "I have a very active immune system and get bitten a lot, developing big red spots," she says. She is currently studying why midges – the bane of so many holidays in Scotland – plague some people and not others. In a study carried out last year involving 10 volunteers, she demonstrated that carbon dioxide and lactic acid were again the most potent chemicals that attracted midges to humans, in addition to urea, palmitic and various amino acids.
"We found that some of the sweat extracts were significantly more attractive than others," she says. "But we've not been able to link the chemical differences to the midges' behavioural response. Work is in progress."
Once that link can be established, scientists hope to create an irresistible decoy, consisting of carbon dioxide, lactic acid and other chemicals. Mosquitoes and midges will then be attracted to the artificial host, and we will no longer have to plaster ourselves with insect repellent. Holidays will never be itchy again."