A crop-destroying caterpillar that has devastated agriculture in Africa is poised to spread into southern Europe for the first time and could even reach Britain, experts are warning.

Fall Army Worm has cost African economies billions of pounds in crop losses since the American pest was first spotted on the continent two years ago, prompting fears of a humanitarian crisis as millions of farming families face destitution and hunger.

No-one knows for certain how Fall Army Worm, a caterpillar – despite its name – regarded as one of the world’s most invasive crop species, crossed the Atlantic.

First spotted in 2016 in Nigeria and in the island state of Sao Tome and Principe, scientists say it is likely that the caterpillar reached Africa aboard a passenger aircraft.

Proving that theory will be tricky, but what is certain is how quickly the pest has spread: female moths are able to cover distances of more than 60 miles a night. As a result, crop infestations have been now been reported in nearly 40 African countries and populations of Fall Army Worm have now reached the fringes of the Sahara itself.