Mosquitoes have been kept away from humans and animals using smoke from fires. The ancient Egyptians and Romans rubbed themselves with highly odorous plants. At the beginning of this century, numerous mosquito balms of plants like clove, cinnamon, lavender, camphor, etc. were developed. The best was citronella oil, which is extracted from a tropical ryegrass. It is still used, in citronella candles, but the effect is weak and brief. During World War II the search for effective mosquito repellents intensified. To this day, the effects of more than 30,000 different repellents have been tested, and only few were found to be effective.

Effective oil-based mosquito repellents. Repellents containing DEET (N,N-diethyl-m-toluamide) and / or dimethyl phthalate were among the best. When used carefully, they can maintain the repellent effect for several hours after application. Instead of using the repellents directly on the skin, clothing can be treated with the repellent. In Danish pharmacies, it is not possible to buy repellents with DEET, however, there are other types of repellents with almost the same effect. For example the Autan repellent is also recommended if you need protection in the tropics.

The modus operandi of mosquito repellents. As mentioned, the mosquito primarily finds its blood host by searching for the warm, moist air that is radiated from the skin. The mosquito has some small hairs on its palps, and these senses moisture in the air. There are many indications that effective mosquito repellents can clog the fine pores of the sensory hairs and prevent the moist air from entering. Therefore, the repellents do not give out an odor that mosquitoes do not like. Furthermore, it is not to be expected that the repellents keep mosquitoes at a distance. The mosquitoes are not confused until they are about to land.

Vitamin B. It is sometimes claimed that taking large quantities vitamin B is mosquito repellent. The effect of vitamin B is a result of parts of the vitamin being excreted through the skin. People, who eat large amounts of vitamin b, often smell of yeast or bread. In controlled studies, including studies done at the Danish National Pest Infestation Laboratory, has failed to show any effect on mosquitoes.

Smoke from Pyrethrin-based coils or sticks, or from tablets that are electrically heated, can keep mosquitoes away from the room or from the terrace. They must be placed so that you sit in the smoke or the smoke is between you and the mosquitoes.

Sound – A flying female mosquito, beat her wings about 320 times per second. This gives a sound with a frequency of 320 Hertz. It is the sound you hear when a mosquito is approaching. The male mosquitoes have good auditory organs on the bushy palps, and they find the females by listening. A trap, which sends out sounds with a frequency of 3-400 wing beatings per second, can catch male mosquitoes. These traps are used for research, but they have no practical significance, since it is the female mosquito that bites. The female mosquito’s auditory sense is not well developed, and it has never been proven to be useful. Nevertheless, new devices that claim keep the mosquitoes away using sound are regularly introduced. They send out tones which are not very loud but have a high frequency of about 15000-20000 Hertz. The frequency is so high, that the human ear can barely hear the sound. There is no reasonable explanation as to why the female mosquitoes should react to this sound. Consequently, there is nothing to suggest that the devices work. There are users of these devices who think that they work. (The World wants to be deceived).

Lights – especially from the ultraviolet part of the spectrum – are appealing to many insects. Several types of insect traps lure the insects with ultraviolet light and capture animals in traps or kill them with electricity. The ultraviolet light attracts mosquitoes, but the traps are not suitable for use outdoors. First, they attract more mosquitoes than they catch, and secondly, they kill many peaceful moths and other insects that fly at night.

Nets. Tulle or other suitable fabrics can be used to cover windows and doors. This is a reasonable way to prevent mosquitoes from entering the house or the caravan.

If too many mosquitoes enter the house, they can be killed with one of the pyrethrin insect repellents for flying insects.

Aedes mosquitoes

Blackflies

Midges

Fig. 36. Of the three Diptera species which attacks humans, mosquitoes the largest. Black flies and midges are the smallest. Here, they are shown in natural size.