"Everything depends on how the summer unfolds. If it's sunny and warm, you will see no ticks or slugs. However the wasps will do very well then," said Lars-Åke Janzon, a biologist at the Swedish Museum of Natural History.
Ticks, a mainstay of Swedish summer, have already been spotted waking from their winter rest. And even Spanish slugs, an invasion species that can wreck havoc on gardens and native slugs, can be active at temperatures around 4 to 5 degrees Celsius .
"They're not rocketing around, but they are moving. These are tough creatures," Janzon said.