Updated on 11 July 2023
Polyphagous Shot-Hole Borer (PSHB)
The polyphagous shot-hole borer beetle (PSHB), Euwallacea fornicatus, is an invasive ambrosia beetle native to Southeast Asia, which has caused significant damage to a wide variety of trees in urban, suburban, natural landscapes, and on farms.
PSHB was first discovered in 2017, in the KwaZulu- Natal Province infesting plane trees. The beetle has spread across South Africa and has infested more than 140 tree species.
The beetle bores into healthy trees, usually branches >35mm, trunks and stems, making round, small holes of ±1mm.
PSHB has a symbiotic relationship with the fungus Fusarium euwallaceae, which the beetle carries in special internal structures and propagates when starting a new tunnel system. The beetle farms the fungus inside the tree as a food source for itself and its larvae. Actions by the fungus-beetle complex ultimately disrupt the flow of nutrients and water that leads to Fusarium dieback and death of highly susceptible host trees.