Christian Veletta, architect at Fonds Belval, explains the installations — which consist of sacks, wool and wood — are designed to stop the oak processionary caterpillars from reaching the ground and transferring themselves to people or animals.
The caterpillars belonging to the oak processionary moth species are known for causing allergic reactions and skin irritations if they come into contact with the skin, triggering all manner of health issues year on year, from spring until summer.
The peculiar contraptions seen on trees in Belval represent a barrier to the caterpillars, as they don’t like passing through the wool, and therefore have no choice but to crawl into the sacks. Even if the creatures don’t crawl into the sacks, Veletta says they will be more visible on the tree trunk than if they were to stay among the leaves at the top of the tree, making it easier to safely remove them. This will also increase awareness among the public to exercise caution in areas where the caterpillars are rampant.
In other cases, pheromones are dispersed to attract the caterpillars and make it easier to capture them. Valetta explains this method was tested last year after seeing similar installations in Luxembourg City parks. At the end of the summer, a report will be drawn up on whether the method was effective. Thus far, no caterpillars have been found in Belval, but this is very much weather-dependent, he says. Around 50 traps have been installed among Belval’s 200 oak trees.
The public is reminded not to approach oak processionary caterpillars or their nests, and to give fallen trees a wide berth. Contact with the caterpillars can trigger conditions such as dermatitis, or cause breathing issues.
