Three tarantulas have been found abandoned outside a boarded-up property, in Blaenavon.
It is understood they had been in a garden for nearly three days - one of the spiders was dead by the time the RSPCA were called
The surviving tarantulas have now been collected by the animal charity's inspectors.
The animal protection charity is appealing for information and said the spiders needed a fairly stable warm temperature and water to survive.