German Spy query-did they use butterflies..?

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I came across an account that claimed during World war II British Intelligence agents in Brazil noticed that persons they suspected of being German agents keep buying framed Butterflies decorations...reportably the British intelligence had their scients try to find if these flutterflies were used a s code for information ..but found nothing..?
Did this really happen or is simply a good yard that wont die?
By the way the only time I heard of butterflies used in spy work is that of a english spy posed as eccentric Butterfly collector actually drew pictures of plans of enemy forts in his butterfly drawings....