Cape Town Is Waging A War On Tree-Killing Vietnamese Beetles

[Image: PSHB / Facebook]

More than 7,000 trees have been affected by tiny invasive beetles from Vietnam that are killing off trees in urban and natural forests.

Since its discovery in KwaZulu-Natal in 2017, the polyphagous shot hole borer (PSHB) has been confirmed in eight of South Africa’s nine provinces, with Limpopo being the only exception.

In Cape Town, the infestation has been particularly severe, with over 7,000 trees confirmed to be infected.

Daily Maverick reports that, initially, the PSHB infestation was observed in crops like pecan and macadamia orchards before spreading to commercial forestry species.

The most unpredictable impact has been on natural and indigenous forests, where a troubling pattern has emerged: the beetle is spreading from urban trees to these native areas. Thousands of trees have already been lost to the tiny beetle as researchers, communities, and municipalities struggle to control its spread.

A research study by Garyn Townsend, Martin Hill, Brett Hurley, and Francois Roets, published in February 2025, revealed that PSHB is impacting nearly all major South African forest types, with the exception of mangrove forests, as they are dominated by host species that are unsuitable for the beetle.

“Many tree species and families had higher than expected infestation rates. An increase in PSHB-attacked trees and infestation severity was observed over the course of the study, with trees having a 7.5% increased chance of PSHB infestations per year and PSHB holes increasing by over 10% annually,”

The study found that over five years, PSHB invaded all but one forest type, with colonization recorded on numerous native tree species. This often led to severe infestations and, in some cases, tree mortality.

Luke Potgieter, invasive species and PSHB researcher for the City of Cape Town, also affiliated to Stellenbosch University, said they were planning on rolling out mass trapping across the city using bottle traps, used to determine whether PSHB is in an area.

“These traps will be largely set out in areas along the leading edge of infestation. That’s really where we can track and have a better understanding of the current distribution of the beetle and where it’s likely to progress,” said Potgieter.

The Department of Agriculture published the amended PSHB control measures on 25 February 2025 as part of the Agricultural Pests Act, highlighting PSHB’s status as a quarantine pest and indicating the reporting procedures for new pests.

The amendment also highlights the prohibition relating to the removal, keeping, planting or cultivation of infested plant/weed.

The DFFE advised that when dealing with infected trees, the first step was to ensure that the damage caused by the PSHB beetle had been properly identified.

To learn more about this tiny pest and how to treat it, check out this informative infographic from Cape Nature.

[Source: Daily Maverick]