The painted grasshopper (Poeklocerus pictus) arrived from India. The 6cm-long insect is blue and yellow.
The specimen was identified by the Food & Environment Research Agency (Fera) after being found on a flight arriving at Stansted Airport.
"The visitor has a voracious appetite and rapidly ate its way through a cabbage plant in the quarantine lab," said Fera entomologist Dr Chris Malumphy.
"Grasshoppers can consume green forage roughly eight times as fast as cattle in proportion to their weight."
Fera said the lone grasshopper will not be able to reproduce and it would have been unlikely to survive the UK climate.
"This insect is an economic pest in Pakistan and India where it reportedly damages a number of food plants including aubergine, citrus, cucurbits, potatoes and tomatoes," Malumphy said.
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