CHENNAI: Residents of nearly half-a-dozen localities near Tambaram are facing an unusual problem. They have been forced to stay indoors after sunset as an army of giant African snails invaded their homes.

The nocturnal creatures have entered kitchens and just about every part of residential buildings — feeding on plants, fruits, vegetables, sand, small stones, cement and lime. “Never before have we experienced this. They are everywhere,” said K Karthikeyan, a resident of Madambakkam.

The recent rains, agricultural department sources said, might have provided a conducive atmosphere for the snails which had sneaked into shops and have been spotted on farmlands, gardens, trees and streets. While many shopkeepers are alarmed over the extent of their spread, several consumers have stopped coming to these shops for fear that vegetables or other articles touched by the snails, said to be non-poisonous, may not be fit for use.

Residential colonies are the worst affected. Every evening, class VI student K Sekar use to play cricket with friends in the open space within his house in Gandhi Nagar, Madambakkam. He doesn’t anymore. Snails don’t like heat and light and seldom survive in hot climate, especially above 30 degrees Celsius. They come out after dark and move in clusters — riding on each other’s backs. Adults are around 7cm tall and 20cm long.

“We don’t know how to fight this menace. We took up the issue with Madambakkam town panchayat officials but there has been little response,” said KC Babu, a resident.

Some residents have found a way to curb the menace. While some collect the snails and sprinkle salt around the area to prevent their movement, other have been burning the snails in groups. On Tuesday, officials from the forest and agricultural departments visited several affected areas and collected a few samples for study. Said to be a highly invasive species, they are known to carry phylophthora fungus that causes root and stem rot in plants and a parasite that can cause illness in humans.