Global climate change in recent years has had many effects on Japan’s weather, with unusual trends such as dangerously hot summers and winters with enough snow to create isolated settlements. Tornadoes and other weather-related disasters that were once unheard of in Japan are not uncommon these days.
The two to three weeks between June and July are the ‘梅雨 / Tsuyu / rainy season’, a humid period of light rain. It was an extremely difficult period for people overseas who were not accustomed to the unique East Asian climate, but in recent years this rainy season has begun to fade away.
The end of the rainy season and the middle of July brings an extremely hot summer.
Summer in Japan is not only hot but also humid and therefore very severe.
Visitors to Japan at this time of year should take care to stay hydrated and look after their health. (In particular, Kyoto, a popular tourist destination, is known for its extremely hot summers and bitterly cold winters.)
There is another problem that can be a problem in summer in Japan.
That is mosquitoes.
If you forget to close the windows at night when it is hot and humid, mosquitoes can invade. Mosquito bites require several dozen minutes of itching. (This is common knowledge in countries where mosquitoes are present…)
Malaria has been eradicated in Japan, so 99% of the damage is only temporary itching, but in recent years there have been reports of new viruses being transmitted, so certain precautions are necessary.
Certain preventive measures … That is definitely to avoid mosquito bites in the first place.
I have heard from research that in Europe and the USA, the mainstream is ‘insect repellent spray’, which is sprayed on clothes or bare skin. What kind of countermeasures do you take in your country?
In Japan, insect repellent sprays are also used, but mainly only during outdoor activities. Most of the time, stationary insect repellents are used indoors. (Many Japanese do not like to get chemicals directly on their skin, belongings or household goods. They like to bathe, so spraying is quickly washed away (^_^;).
With changes in the natural environment and urbanisation, mosquitoes themselves are decreasing in number, but they still occur to a certain extent in rural areas with many mountains and rivers. This is even more so in the past, when nature was more abundant.
Yes, it is. To put it bluntly, the history of summer in Japan has been one of battles with mosquitoes…
In the olden days, mosquito control measures included reducing body exposure, dispelling mosquitoes with long-haired tassels, isolating certain parts of the living space with cloth and other materials, and driving them away with smoke from burning plants and trees that mosquitoes might not like.
Mosquito nets were commonly used in Japan until around the 1960s.
However, these methods are not efficient as human activities have become more diverse over time.
The insecticidal effect of pyrethrum ingredients has been known since the 17th century. In the region of Dalmatia, facing the Adriatic Sea in south-west Europe, it was discovered that the chrysanthemum, with its neat white petals, contained an insecticidal component, and since then it has been actively cultivated and increased in production, eventually spreading to many countries.
Pyrethrins, which are found in abundance at the base of the pistil of the pyrethrum flower – the very centre of the flower – have the effect of inhibiting the nervous effects of insects. This is then dried and powdered and sprayed or burned. Initially, this method was used to control fleas, ticks and flies rather than mosquitoes (this type of product still exists).
In 1885, Mr H. E. Amoore, a plant importer from San Francisco, met with Ueyama Eiichiro, a Japanese agricultural researcher, in search of new plant species. Ueyama presented Amoore with seedlings of bamboo, shuro, chrysanthemum and other plants from Japan. In return, the following year Amoore sent him seeds of pyrethrum, which were valuable at the time.
After receiving pyrethrum seeds from Mr Amoore, Ueyama began by growing them on his own farmland and immersed himself in research. Through repeated trial and error, he gained an understanding of the growing environment, such as its adaptability to continuous cropping and to the soil, and also focused his efforts on verifying its effectiveness against pests.
Ueyama Eiichiro
Convinced of the potential of pyrethrum’s insecticidal properties, Ueyama made a series of trips, which could be described as a “pilgrimage”, to increase the number of locations where pyrethrum was cultivated from his home region to the rest of the prefecture and from the prefecture to all parts of the country.
The new plant, which at the time had never been seen before and was not known to be profitable, caused some controversy at first, even among local farmers. However, thanks to Ueyama’s passionate persuasion, cultivation gradually began, and the circle eventually spread nationwide.
Even when the production of pyrethrum, the raw material, was established, the product itself for insect control had to be conceived. At first, the company produced powdered products in accordance with the insecticidal products that had been produced until then, but Ueyama thought that development would not be possible without the production of products that could be used more easily and efficiently at any time and in any place, and that were highly effective.
During one of his visits to Tokyo, Ueyama met Ito Miki, an incense stick maker, and in the course of their discussions, they came up with the idea of making an ‘incense stick insecticide’ by kneading pyrethrum insecticidal ingredients into the incense stick during its production process.
Ueyama immediately returned to his hometown, hired an incense maker, and after many trials and errors, finally completed the product in 1890 and put it on the market as ‘金鳥香 / Kinchōkō’, a mosquito repellent incense stick.
Kinchōkō’ sold very well and immediately gained a lot of support, but Ueyama himself was still not completely satisfied with the product.
The thin incense sticks produced little smoke, and the smoke emission time was only around 40 minutes, so it took a lot of incense sticks to achieve a long-lasting insect repellent effect. The ultimate goal of Kamiyama was to develop an insect repellent incense stick that would last for several hours once lit.
And the clue to the answer was found in an unexpected place…