This could be about the British TV serial for children created by Joy Whitby. It was first broadcast in 1971. This series was filmed on location in London, Milford Haven and Corsica.
The series centers on three brothers, nicknamed Toughy (wants to be a soldier), Smarty (clever), and Mouse (likes cheese). Their real names are not revealed. Presumably orphaned (their parents are never seen or mentioned), they have lived with a succession of different people – 'some nice and some nasty, but no-one who they liked in particular'. Being boisterous, adventurous and imaginative, they are regularly in trouble and consequently resent their situation. Eventually, they decide to run away to sea. After escaping, they hitch a ride courtesy of the bizarre Elderly Boy in his converted lifeboat. They eventually arrive on an apparently uninhabited island, (grasshopper island of course) where they set up home. After a while they discover that the island is home to the eccentric grasshopper expert Cornelius Button and his feisty housekeeper Lupus. After making friends with their new neighbours, they join forces with them to defeat the unsavoury Doctor Hopper.
But it's not about that or about the book that was based on the TV show either.
It could be about giant grasshoppers duking it out with farmers and taking over their crops.
It could be about a famous grasshopper named Wilbur. Wilbur was Goofy's pet grasshopper. He first appeard in the short "Goofy and Wilbur" and has since had a part in the Mickey Mouse Club.
Little Known Fact: According to the TV special, "On Vacation With Mickey Mouse and Friends", he is Jiminy Crickets nephew.
But, alas, it's not about Wilbur either. You will just have to go check it out for yourself. Only then will you really understand fully what this cache is all about.