As the number of skin blistering cases caused by the acidic venom of rove beetles increases in parts of China, experts are warning the public not to swat or crush the insects, and instead to gently brush them off with a napkin or blow them away to avoid skin irritation.

In recent weeks, short videos showing swarms of the reddish, black-striped insects covering scaffolding and mesh nets at a construction site in Luoyang, Henan province, have circulated widely online.

Since late September, medical and disease control experts in the provinces of Anhui, Shandong and Shaanxi have reported increasing numbers of patients developing painful red blisters after coming into contact with the insect.

Peng Jun, a dermatologist at Dezhou Hospital under the Qilu Hospital of Shandong University, said late last month that his department has been receiving about eight to 10 rove beetle-related cases per day — a significant increase compared with last year.

Disease control authorities in Suzhou, Anhui, said last week that after persistent rainy weather, many residents noticed an influx of small flying insects in their homes, later identified as rove beetles.

Liu Qiyong, a researcher at the Chinese Center for Disease Control and Prevention, said at a news conference that rove beetles are most active in moist environments with temperatures around 25 C and humidity near 80 percent. They tend to inhabit areas with tall grass, shrubs and stagnant water.

If a rove beetle is crushed or swatted against the skin, it releases a highly acidic venom with a pH level comparable to that of concentrated sulfuric acid, which can cause rashes and blisters of varying severity.

Experts advise that if a rove beetle lands on the skin, people should gently blow it away or brush it off with an object rather than slapping it to avoid contact with its venom.

For those exposed to the venom, Liu recommends immediately rinsing the affected area with soap and water for at least 15 minutes. Medical attention should be sought if symptoms such as darkening skin, persistent fever, spreading redness or rash develop, he added.