The presence of the Asian long-horned beetle was first recorded in the canton of Fribourg in 2011.
Since then the insect has spread to six other cantons — Basel-City, Basel-Country, Thurgau, Zurich and Lucerne, with the largest concentration found in Winterthur, the federal office of the environment (BAFU) says.
The beetles arrive from Asia in wood crates and other packaging, which has led Swiss customs officials to redouble inspections of shipments using such materials.
Even if the total number of beetles counted last year — 155 — seems small, the Swiss federal government is taking the threat seriously.
The insects pose a concern because it is very difficult to kill off the larvae, which bore into tree trunks and branches, weakening their structure and encouraging fungal growth.
The beetle and other non-native wood-boring pests cause an estimated $3.5 billion in annual damages in the United States, where the Asian insect first surfaced in the 1990s, according to reports.
Given the potential risk, federal authorities in Switzerland are taking no chances.
During a visit to Beijing last month, Swiss Environment MInister Doris Leuthard signed a cooperation agreement with the Chinese minister of the environment to tackle the issue.
Scientists from the Swiss federal institute for forest, snow and landscape research also visited China to find out more about the pest, Tages Anzeiger reported on Wednesday.
“We want to prevent long-horned beetles from continuing to expand in Switzerland,” Josef Hess, deputy director of BAFU is quoted as saying.
Last year, authorities burned 130 infested trees in Winterthur, apparently the only foolproof way of exterminating the insects.
At Swiss customs check points, all goods packed in wood that do not come from the European Union must be declared.
Experts can subject such packaging to extreme heat — if there are any beetles in the packaging they will die if exposed to heat of more than 56 degrees Celsius, Tages Anzeiger said.
But the best way is to ensure that the wood boxes and cartons are treated before they leave China, which is what Chinese authorities have pledged to do, the newspaper said.
Switzerland is also working with other Asian countries to address the same issue.
Meanwhile, dogs trained to detect the beetles are being used by Swiss customs officials at the port of Basel on the Rhine River and at Winterthur.