Swarms of these insects have been attracted to the wooden walls and pillars of the “Grand Ring”, a centrepiece of the expo and its main thoroughfare. Visitors have been forced to fend the flying insects off to avoid swallowing or inhaling them, raising concerns about potential health risks.
“They landed on the bread I was eating. There are so many of them around and it’s disgusting,” said Toma Masatani, a 23-year-old graduate school student visiting the expo with friends from Saitama, near Tokyo, as quoted by Kyodo news agency.
Expo organisers have identified the insects as chironomids, a species that does not bite or suck blood, according to The Japan News. However, their dead bodies can pose a health hazard: inhaling or ingesting them can trigger asthma and other allergic reactions.
“Wearing a face mask is advisable for those with asthma,” said Koichiro Kawai, a professor emeritus at Hiroshima University specialising in the species, in an interview with Kyodo.
Experts predict the infestation will persist until late autumn. The bugs are believed to have spawned in the Water Plaza, a large seawater storage area on the expo grounds, which is built on reclaimed land over a former landfill.
