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Cambridge University Science Magazine
When thinking of the weird and wonderful, few animals seem to fit the bill as well as the large blue butterfly. This unassuming insect might look like any other, but its caterpillars hide a sinister secret. Left out in the open to fend for themselves, they are adopted by ants, mistaken for one of the ants’ own grubs which has strayed far from the safety of the nest. Once carried back to the colony by the ants, the caterpillars are terrible guests and proceed to eat the real ant grubs!

It turns out that the large blue butterfly caterpillars mimic the chemical signature of the ant grubs, acting as social parasites not unlike cuckoos. This mimicry is remarkably specific to a particular species of red ant. This was not well understood for much of the large blue’s documented history in the UK, and, unfortunately, this lack of understanding contributed to the extinction of the large blue from the UK in 1979. However, research into the host ant species and improved management allowed the butterfly to be successfully reintroduced just a few years later. The UK now hosts some of the densest populations of the large blue butterfly anywhere in the world, making this a rare but welcome conservation success story.

Article by Matt Hayes. Image copyright Didier Descouens under CC BY​-SA 4.0