Hot summer fuels surge in stinging insects in Carinthia

A hot, dry summer helped stinging insects and other pests spread across Carinthia, while some introduced species became increasingly established, ORF reported.

Wasp numbers surged after the warm, dry spring, and hornets and horseflies were also seen more frequently. Laura Waldner, head of the zoological department at the Kärnten.museum, said the rise in horseflies was probably linked to the previous year, which had been relatively wet. Their larvae develop over several years in damp soil, she said.

The introduced tiger mosquito, which has been detected in the region since 2022, was recorded 50 times in Klagenfurt this summer. The species can transmit diseases including dengue fever and is expected to become established in the region. Its eggs can stick to flowerpots and tubs, so Waldner advised cleaning them before bringing them indoors for the winter. Otherwise, the eggs can hatch when water is added in spring.

The dry conditions, however, were unfavourable for the native house mosquito, which needs standing water to reproduce.

The pine processionary moth, another species moving north from warmer areas, has also spread into Carinthia. It has been detected since 2016 and was previously seen in the Canal Valley. Its silk nests are found in the crowns of pine trees, while hairs from its caterpillars can cause allergic reactions. Waldner said warmer temperatures were making the region more suitable for species that previously found it too cool.

Dry conditions also benefited bark beetles, which continued to cause serious problems in some places. Leaf miner moths and Chinese ladybirds have become established in Carinthia as well, according to zoologist Christian Wieser. He said native ladybirds had since returned and the two populations appeared to have reached a balance.

By contrast, the Spanish slug was difficult to find this year because of the drought. The species was originally introduced through plant imports. Wieser said he had recorded as many as 24,000 slugs in a single-family home’s garden in one year since beginning his records in 2013. This year, he found fewer than 1,500.

Insects are useful indicators of climate change because they respond sensitively to temperature and moisture. In general, animals with shorter life cycles can adapt more easily to changing climatic conditions.