Many schools and government agencies in central Vietnam have had to close temporarily as residents attempt to battle a destructive swarm of inchworms, a species of caterpillar native to North America.
Local people in Anh Son District of Nghe An Province said this was the first time their environment had been "attacked" by the inchworms which are notorious for their voracious appetite for plant material.
Experts say the species is spreading fast and reaching densities of up to hundreds in one square meter. At schools, where flamboyant trees their favorite - are planted, the "worms" can be found on walls, corridors, furniture and even the clothes of students and teachers.
Nguyen Dinh Tung, vice chairman of Cam Son Commune's People's Committee, said that although some schools had yet to close, classes were continuously interrupted by the caterpillars, which affected both studying and teaching.
"Many students were so scared they fainted in class," Tung said, expressing concerns that the inchworms (which are also known as "loopers" because they arch when they crawl) would continue to grow in numbers.
Nguyen Van Luu, chief of Anh Son District Plant Protection Office, said local authorities have ordered agencies to spray pesticides, and asked people in affected areas to cut down otherwise healthy trees to deny the species food and habitat.
Related agencies in Nghe An have yet to identify a cause for the epidemic.
Local people, on the other hand, said spraying pesticide wasn't a good solution, because the caterpillars are everywhere.
The spray, if not controlled effectively, could pose risks to people who use it, they said. Some predicted that the epidemic would get worse when the leaves fall in autumn, prompting the insect to spread out more for food.
The same situation was also reported in Thach Thanh District of Thanh Hoa Province.