Argentina’s agricultural inspection agency has said it is keeping up efforts to control a locust infestation threatening crops in at least three states.

The agency said it had controlled 31 new outbreaks of the insect in the states of Catamarca, Santiago del Estero and Cordoba.

The plague affected about 700,000ha (1.7m acres), said the Rural Confederations of Argentina in an emailed statement. It is the worst infestation since 1954, according to Juan Pablo Karnatz, president of a farmers’ association in Santiago del Estero.

The farmers warned the government of the first signs of the infestation in July 2015 but authorities did not respond adequately, said Karnatz. Only after new officials took charge of the inspection agency did the government begin to attack the problem head on, he said.

“Before the farmers were combating the plague on their own,” Karnatz said.

Time is of the essence, the farmers say. If the fumigators don’t find the young insects before they mature in 10 days they form swarms of locusts in search of food. The other challenge is discovering unsighted pockets of locusts.