In Japan, many people may have felt that this summer there were fewer mosquitoes than in normal years. Koichi Goka, head of the Ecological Risk Assessment and Control Section of the National Institute of Environmental Studies' Biodiversity Division, was no exception. Even in creatures that are familiar to humans, such as mosquitoes, signs of environmental change may be seen. The summer was so hot that many people said they were bitten less often by mosquitoes, according to a TV show. There seemed to be few pests around in Tsukuba, Ibaraki Prefecture, where this author lives.
The only air conditioner in my apartment died in the middle of the sweltering heat this August, and I had to spend around a week with my windows fully open until a new one arrived.
I used to be annoyed by the humming of mosquitoes in my earlobe after they sneaked into my apartment room from the gap of window screens at night. This would cause me to get hardly any sleep and compel me to light mosquito repellent incense, which stunk out of my clothes.
Yet this summer, not a single insect came into my pitch-dark room, even if I had kept the screens open. The image that the hotter it is, the more active they will become. Insects are heterothermic animals. In fact, it's the other way around: insects become unable to move if it's too hot, and eventually die in some cases.
Tiger mosquitoes, the most common in Japan, are said to be most active at 25 to 30 degrees Celsius. If the temperature surpasses 35 C, it is said that they will be unable to fly and wait in hiding in cooler places, such as forests and bushes.
The temperature of the walls of concrete housing soared ultrahigh on this summer's extremely hot days, making room temperatures inside hardly go down at night. There were so few mosquitoes flying in, believed to be the reason for this.
The air conditioner glitch at my apartment made me realize how extremely hot this summer was, to the extent of abnormally hampering the emergence of mosquitoes. As an environmental researcher, I couldn't help but to think about the environmental change that had brought this summer's ultrahigh heat.
The cooler temperatures may cause mosquitoes to increase as we move into autumn. Adult mosquitoes that have survived the sweltering summer and their offspring may fly around and sting humans more often.
In 2014, Tokyo was hit with a sudden outbreak of dengue fever, a tropical infectious disease borne by mosquitoes.
It is not known what kind of diseases may be borne by mosquitoes in this age of advanced globalization. It is important to take precautions to avoid getting bitten by them, such as bug spray and anti-insect mats.
I remember seeing a swarm of mosquitoes in my college days.
One summer, I was on a solo motorbike tour through Hokkaido on a vacation and was preparing dinner after pitching a tent at a campsite by a lake when a swarm of mosquitoes emerged from a forest and attacked me like crazy.
Bug spray didn't work at all, and even when I moved around, the mosquitoes chased me. I was not able to run into my tent because I was using fire. With no other solution, I had to start the bike engine, sit by the muffler exhaust, and eat dinner while letting the exhaust gas blow the mosquitoes away. With my head exposed to the gas, I can never forget the stench of the meal.