By Gofaone Motsamai
The unusual presence of green stinkbugs in offices, homes and public buildings is no cause for concern, according to Professor Johnnie van den Berg from the Unit for Environmental Sciences and Management at North-West University (NWU).
“There have been surges in the numbers of many pest and non-pest insects over the last two to three months. This is ascribed to the good rains that were experienced over most of the region,” says Prof van den Berg. He explains that when rainfall is abundant, the host plants of herbivorous insects become more widespread, increasing their chances of survival into adulthood.
Stinkbugs, including the Nezara viridula species, commonly known as the southern green stinkbug, feed on a wide variety of plants. This, together with the lush environments found after good rains, boosts their ability to reproduce and survive. While their sudden appearance indoors may be unsettling, Prof van den Berg says they pose no direct or indirect health risks to humans.
“It is only when you aggravate them or touch them that they may emit a bad odour, which is aimed at scaring off predators. The incidence of humans showing allergic reactions to such emitted chemicals is believed to be extremely low,” he says.
Prof van den Berg adds that although stinkbugs can affect crops such as soybeans and vegetables, their presence in residential or commercial buildings is mostly harmless. As winter temperatures begin to set in, these bugs are expected to disappear naturally.
“It is relatively common for certain insects like Nezara viridula to start aggregating during the colder months of the year. Ladybirds are also known to do this. These bugs move to more favourable environments, such as homes, where it is warmer and there is no frost.”
No insecticide application is necessary, as these aggregations are temporary and unlikely to lead to reinfestation. “The best thing to do is to sweep them up or off the roof, or out of the corners, and throw them outside,” advises Prof van den Berg
Professor Johnnie van den Berg
