Thousands of "cascarudos", as they are known in Argentina, have taken over parks and gardens in the town of Santa Isabel, in the central province of La Pampa, ABC News reported.
They have also been found in the roofs of houses, where they hide in dark holes and spaces during the day.
Biologists say that unusually heavy rains for this time of the season combined with high temperatures made the bugs reproduce in high numbers.
"We had more rainfall, therefore more humidity, and this, together with the heat we are experiencing, created a favourable climate for the development of these little animals," Santa Isabel deputy mayor Cristian Echegara said.
Mr Echegaray told the AP the town decided to shut down street and public building lights for the past three days to let the visitors "go away and find another town".
The blackout has been effective, and the number of beetles has decreased dramatically.
RHM/PR