A massive locust invasion has destroyed thousands of hectares of crops in northwest India, authorities said, with some experts on Friday terming it the worst such attack in 25 years.

While officials have attempted to tackle the swarm with pesticides, farmers have deployed drums to drive away the insects, with videos showing schoolgirls banging on steel plates - due to local beliefs that loud noise repels locusts. The invasion has damaged crops in half a dozen districts in the northwestern state of Gujarat, local government official Punamchand Parmar said Thursday.

More than 5,000 hectares (12,000 acres) have been devastated in one district alone, Parmar said. "Nearly 25 percent of the locusts had been destroyed using pesticide. However, it will take another 4-5 days to exterminate the insects completely," he added.

"Their flight path was initially towards Pakistan but due to change in wind direction and moisture, they landed in... north Gujarat," he said. The head of the entomology department at Gujarat's Anand Agriculture University, P. K. Borad, told AFP: "This is the worst locust attack witnessed in Gujarat in over two decades or so."

"Such a huge swarm of locust was last seen in 1994," he added. The state's agriculture minister R. C. Faldu said that from Friday onwards, 100 tractors carrying pesticides would be sent to the affected villages to get rid of the insects.

But villagers were not leaving anything to chance, with many walking around the affected farms and banging drums to chase away the insects. "We have lost everything in our village," said one man.

Copyright Agence France-Presse, 2019