Image caption Some farmers are looking at losses of some 20-30% of the crop

Love them or hate them, they are a firm fixture on most Christmas dinner plates, but it seems the humble Brussels sprout is under threat.

A marauding moth - the diamondback - arrived in the UK earlier than expected this year and in unprecedented numbers.

Its larvae munch their way through the leaves of sprouts at a devastating rate.

Farmers in Northern Ireland are seeing the damage too.

Image copyright UKmoths.org.uk Image caption Farmer Steven Murdock said 20-30% of his sprout crop had fallen prey to the diamondback moth

Also known as the cabbage moth, it is thought to originate in the Mediterranean, but is now widespread.

Should we be worried?

Farmer Steven Murdock has 20 acres of sprouts near Comber.

"The first planting of sprouts that we would do would be mid-April. The early planted sprouts weren't touched at all," he said.

"The second early batch of sprouts, in May, were badly affected.

"It doesn't affect the growth, it damages it. It gives the leaves a windowing effect, like it's been eaten by caterpillars but not the whole way through."

He said he was looking at 20-30% of the crop being lost.

"We are under price pressure and can't really afford the losses," he said.

But Mr Murdock reassured people they would still have their sprouts.

"We do grow other varieties," he said. "They might not have big sprouts, the size might not be there, but the quality definitely will."