Although the spider-like arachnids with a size of up to 18 centimetres are completely non-venomous, they're clumping up by the hundreds on walls, castles and industrial ruins, forcing people to spend an inordinate amount of time cleaning them off, according to Die Welt newspaper.
This particular species of daddy longlegs is thought to have arrived in Europe a decade ago and then began spreading, the paper reported.
They were first spotted in the Netherlands, but have since been found in Germany, Switzerland and Austria.
North Rhine-Westphalia, particularly the Ruhr region, is one of the invasion's focal points, according to Matthias Kaiser, insect expert at NRW's Office for Nature, Environment and Consumer Protection.
He said the animals would have found it difficult to come to Germany by themselves on foot, so he suspects they hitched a ride on imported produce from the Netherlands. He told Die Welt they need this kind of help to spread so far.
These daddy longlegs are likely to stay in Germany. Although they die off during the winter, their egg deposits remain, resulting in a new generation during the next warm season.
Luckily they are unlikely to displace native animal species, according to state officials. In fact, they may even provide new sustenance to predatory birds or spiders, Die Welt said.
Experts believe the animals will continue their spread toward the southeast of Europe.