We have confirmed that the insects currently present in large numbers at the Expo site are Chironomus salinarius (hereinafter referred to as "Chironomid midges")
At present, swarms of the chironomid midges are occurring particularly during the evening and night. The insects are most prevalent on the Grand Ring (Skywalk) on the south side of the Expo site and the waterside areas to the east and west of the Grand Ring. However, their swarming locations vary depending on weather conditions and they have been observed over a wide area of the Expo site.
Chironomid midges are not reported to transmit any diseases and do not sting or bite.
To date, the Association has sprayed rainwater drainage pits, etc. with a chironomid growth inhibitor, and implemented measures to prevent infestation with repellents, cleaning, and disinfection at Association facilities. In addition, the Association is supporting the use of repellents to prevent infestations, cleaning and disinfection at shops and other facilities.
The Association is collaborating with specialists to identify the source of the outbreaks and investigate effective countermeasures that also take into account human health and environmental effects.
For more information, please see the Announcement.

https://www.expo2025.or.jp/en/news/news-20250527-02/ 

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