British border officials have seized 94 kilogrammes (207 pounds) of dried caterpillars from a man who claimed they were "for personal consumption", the Home Office said.
Officials at Gatwick Airport, south of London, found the bugs in the luggage of a 22-year-old man who flew in from Burkina Faso via Istanbul on February 23.
"When officers checked his luggage they discovered tens of thousands of dried caterpillars shrink-wrapped in cellophane, which had been packed into four hessian bags," the interior ministry said.
"The man claimed that they were for personal consumption and that they were to be used as food."
Insects are commonly eaten in many parts of Africa, Asia and Latin America.
But the caterpillars breached British rules on importing products of animal origin and will be destroyed.
"This was an unusual seizure but the vigilance of our officers has stopped these dried insects from entering the UK, and possibly posing a risk to our food chain," said Ingrid Smith of Britain's Border Force.
"I would warn travellers not to attempt to bring any products of animal origin into the UK without a permit, as they may not have been inspected to appropriate standards and may contain diseases."
Restrictions apply in Britain to the importation of meat, dairy, fish, eggs and honey, as well as some fruit, vegetables and plants.
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