The woman from Dumfries unwittingly carried the creature home in a bunch of bananas she bought at a local store.
She called the Scottish SPCA, who identified the creature as a desert hairy scorpion.
Although not deadly, the native to North America can have a painful bite.
The animal organisation is looking for a home for the scorpion after the find on March 7.
Rescue officer Tricia Smith: "The lady was terrified when she called us, although she had managed to contain the scorpion in a jar.
"Desert hairy scorpions aren't deadly but, if bitten, the pain could vary from that of a bee-sting to intense inflammation and sickness.
"It's just bigger than a fifty pence piece at the moment, indicating it's quite young as an adult can reach up to six inches long.
"We're hopeful we'll soon be able to find this scorpion a home with an experienced and knowledgeable owner where it can receive the care it needs."
