Photo 1. A nest of pine processionary caterpillars on a black pine (Photo by M. Randić)
The pine processionary moth
Many pine cultures were planted in our coastal regions as well as on the Kvarner islands in the past. Ambroz Haračić, the natural scientist of Lošinj, is responsible for planting pine trees in Forest Park Čikat. The pine processionary (Thaumetopoea pityocampa), a nocturnal moth, is tied to the pines of the Cres-Lošinj islands, in particular to the black pine and also the Aleppo pine, which was the most planted pine in Forest Park Čikat. Hair-covered caterpillars feed on pine needles and make silky nests in pine trees. These nests can easily be seen on pine branches. The caterpillars spend the winter in these fairly large, sphere-like nests and in early spring they leave them in long processions to find a spot to pupate. In these long processions the caterpillars meander across the ground, where they then pupate.
When caterpillar hairs come into contact with human skin and mucous membranes (the eyes in particular) or, less common, with the respiratory tract, they can cause health problems in people. It has long been known that the hairs of the pine processionary caterpillar are venomous. Certain types of hairs on the caterpillar are hollow and connected to venom glands. The venom contains active proteins, some 70 different types, including thaumetopoein, while the most important active substance is probably histamine, along with seven types of protein that cause allergic reactions. That is why touching the hairs causes allergies, dermatitis (skin inflammation), burns, itchy rashes and conjunctivitis. The hairs also cause serious problems for domestic animals, especially dogs, as they can come more easily into close contact with the caterpillars.
At Public Institution Priroda we received an enquiry from Radio Jadranka of Mali Lošinj asking who was responsible for removing the pine processionary caterpillar nests from the stricken trees in the protected Forest Park Čikat. Considering we have never had a similar enquiry, we got in touch with offices that could have something to say about a possible solution. Up to date, Hrvatske Šume (Croatian Forest Enterprise) has not been engaged in removing the caterpillar nests in the forest park and, given the height of the pine branches, there is no technical equipment available at present by which the nests could be removed from the very high branches. We were told by the Mali Lošinj Branch Office of the Public Health Institute that to the best of their knowledge there have been no health problems caused in people so far by the caterpillars. The Veterinary Clinic of Mali Lošinj, however, did confirm there have been cases on the Cres-Lošinj islands of serious health issues in dogs that came into close contact with the caterpillars.
Our conclusion is that nests of pine processionary caterpillars will continue to occur every year, with lesser or greater intensity. Depending on various ecological factors, some years there will be more nests, and other years, less. People visiting the forest part should be made aware of the dangers that could result from exposure to the caterpillars and their hairs. It would be wise to provide information to visitors through broadcasts on the local radio station, for example, or perhaps on a flyer handed out to visitors and tourists to Lošinj in the early spring. In our opinion, removing caterpillar nests could be beneficial in those areas of the forest park which attract large numbers of people or in the vicinity of certain facilities, if the caterpillars in such locations are seen as presenting a frequent health issue.