The Marimurtra Botanical Garden is not only a space dedicated to the conservation and study of plant biodiversity, but also serves as a sentinel for its surrounding environment. This year, the Garden is working closely with the Plant Health Services of the Government of Catalonia (Generalitat de Catalunya) in an important prevention campaign. Marimurtra has been selected as one of the few locations across Catalonia where trial traps have been installed to detect the presence of a potentially invasive insect: the Japanese beetle (Popillia japonica).
Although there is currently no evidence that this pest has reached our territory, early detection is the most effective tool for protecting our ecosystems and crops.
What is Popillia japonica?
The Japanese beetle is a coleopteran insect distinguished by being a highly polyphagous species; in other words, it feeds on an exceptionally wide range of plants.
Adult beetles measure approximately 15 mm in length and 10 mm in width, and display distinctive metallic colouring. Their larvae, which live underground, can range from 1.5 to 32 mm in length, with a maximum diameter of between 5 and 7 mm.
Why are we on alert?
Despite its Asian origin, this insect has proved to be a true “hitchhiker”. It can easily spread and colonise new territories by travelling unnoticed in both commercial goods and travellers’ luggage. In Europe, the first specimens were detected in Italy in 2014, and since then monitoring the species has become a priority.
To illustrate its ability to spread, on 20 June 2025 an adult specimen was intercepted at A Coruña Airport after travelling concealed inside the suitcase of a passenger arriving from Milan.
What damage can it cause to our flora?
Under our climatic conditions, adults may be found on host plants from May to October. This pest is particularly dangerous because both larvae and adults damage plants, each in a different way:
- Damage caused by the larvae: females prefer to lay their eggs (oviposition) in lawns, grasslands or moist meadows, where conditions are ideal. There, the larvae hatch and feed on plant roots. This drastically reduces the ability of turf or grassland to absorb water and nutrients from the soil, leaving it severely weakened and dried out.
- Damage caused by the adults: adults show a preference for grapevines, fruit crops and various members of the rose family (Rosaceae). They are highly gregarious, meaning that large numbers gather on the same plant. When feeding on leaves, they consume only the soft tissue, leaving the veins intact. This characteristic type of damage is known as leaf skeletonisation. They can also cause direct damage to fruits.
How do the Marimurtra traps work?
To carry out this preventive monitoring, the Government of Catalonia has provided the Garden with Ellisco-type traps. These devices are specifically designed to capture both adult males and females. The traps operate using a highly specific combination of attractants: a sex pheromone and several floral attractants. If any individuals are present in the area, they will be drawn to the trap before they are able to establish a population, allowing the authorities to be notified immediately.
Remaining vigilant and taking part in these pilot trials reaffirms the Carl Faust Foundation’s commitment to protecting and preserving biodiversity.
Stay tuned to our blog and social media channels to follow the progress of this collaboration.
