The 47-year-old from Herford, North Rhine-Westphalia, called police after what she thought was a spider turned out to be a Mediterranean scorpion.
Officers arrived to find she had trapped the creature under a water glass.
An expert summoned to the scene correctly identified the scorpion as the harmless Mediterranean variety.
But that means that the arachnid had been lurking in her bedroom for at least three months, as her last holiday had been in August.
The creature must have stowed away in her luggage during the trip and been unwittingly smuggled back to Germany.