Tokyo >> People aren’t the only ones affected by heat waves.
High temperatures recorded over an extended period this summer have apparently caused insects, such as mosquitoes and beetles, to meet an untimely demise across the country.
“I think there are fewer mosquitoes around because of the intense heat,” said Takeo Yamauchi, curator at the Hyogo Prefecture-run Museum of Nature and Human Activities.
“Mosquito larvae live in water, especially in small puddles, but if the heat continues and it doesn’t rain for a long time, the puddles dry up and the larvae there all die,” he explained.
“There have also been research reports that the activities of mosquitoes slow down when the temperature rises to about (95 degrees) or higher.”
According to the Meteorological Agency, its 927 weather monitoring locations across the nation marked daily highs of 95 degrees or higher 3,127 times in July compared to 812 in 2017.
That’s likely had an effect on mosquitoes and why many people might have noticed fewer of them around this year.
Yamauchi, who is also an associate professor researching arthropods at the University of Hyogo’s School of Human Science and Environment, said the prolonged heat and lack of rainfall probably affect other insects’ longevity, too, such as beetles, noting that the conditions cause many to die while they are still pupae or larvae.
Yoshimi Okamoto, manager of Kabutomushi Dome (Beetle Dome) in the Hyogo Prefecture town of Ichikawa, said: “It’s extremely hot this year and it hasn’t rained in this area, so the ground has dried up. Beetles live in places such as moist soil and underneath leaves, but since the netted area has become all arid, they have nowhere to escape to.”
The venue, where children can come in contact with hundreds of Japanese horned beetles inside a 1,020-square-meter netted area of forest, closed for the season in August about a week earlier than usual, as many of the beetles were unable to survive the heat.
Okamoto said about 3,000 beetles died since the facility opened June 23, although the longevity of the facility’s bugs is shortened because children who visit are free to touch them.
Katsuhiko Morigami of Kuwachan House, which supplies beetles to the facility, said his company tried to procure the creatures from other parts of the country but they were not available.
“We’ve never had a situation like this,” he said. “Normally, if we let the beetles go (inside the netted area) in the morning, we can collect them again in the afternoon, but that didn’t happen this year. They’d all die by the afternoon because of the heat.”
But not everyone is convinced that insects can be significantly affected by high temperatures.
“It’s probably just an impression or imagination,” Shigehiko Shiyake, curator of the Laboratory of Entomology at the Osaka Museum of Natural History, said of recent news reports that fewer mosquitoes are around this summer due to the heat.
“It is true that insects don’t like hot weather. They don’t like the cold either. They’re just like people as we’re all living things on this planet,” he said. “But we can’t say anything for sure unless we gather the necessary data. We can’t be sure that this is something peculiar to this year because it’s essentially hot every summer.”
Some facilities showcasing bugs made sure their star attractions were not affected by the natural elements.
At Minoo Park Insect Museum in Osaka Prefecture, temperatures are carefully controlled so that the butterflies, beetles and other critters there are safe, according to Hiroshi Nakamine, head of the facility.
“We don’t have insects dying here and there at our park,” he said.