The man, in his 50s, was taken to Dunedin Hospital's accident and emergency department with moderate injuries.
A St John responding officer said it appeared the man had been stung about 30 times.
The attack took place amid a spike in wasp numbers in the city. A1 Pest Services Otago owner-operator Craig Legg said staff were destroying about 10 nests a day - more than in any other of the 25 years he had been in business.
The Ministry of Health recommends treating wasp bites with soap and cold water, then using an anti-sting ointment or a paste made of baking soda and cold water. Ice compresses can also be used to reduce swelling.