The enigmatic, rare ‘large blue butterfly’ was pronounced extinct in the UK in 1979. A large scale conservation program and some innovative research and science studies have bought these beautiful butterflies back to the UK. Their reintroduction and continual management means they can now be found and thriving at 33 sites across the South West.
And all due to a particular species of red ant and significant conservation efforts and land management at these special sites.
The adult large Blue female has a life span of 5-7 days and in this time mates and lays small white eggs on the flowers of wild thyme or marjoram, from these eggs, small light brown caterpillars emerge and eat the flower head and seeds for the first few weeks of their lives.
Down below these plants the workers of the red ant Myrmica Sabuleti are busy bringing back food for their young which are meticulously cared for, safe for now in their underground nests.
After a few weeks the caterpillar, falls to the ground and lies in wait for the red ants. the Caterpillar tricks the red ant into believing its one off their own young escaped from the nest. They distort their bodies and release a unique, sweet smelling pheromone making the ant believe that it’s one off its own larvae. The imposter is gathered by the ant and taken back into the nest into the brooding chamber. The disguised caterpillar is cared for by the worker ants happily surrounded by its new source of food. The caterpillar picks of the largest larvae first and cleverly knows to wait patiently for the smaller eggs to hatch and the larvae to grow before consuming them.
This unique phenomena is known as social parasitism and is often seen in many wasp, bee and ant species, where one species is reliant on another to survive.
Hidden in plain sight and after several months of eating its ant siblings. it forms its chrysalis and several months later emerges from underground as a beautiful Large Blue Butterfly.
It took years of studies by Professor Jeremy Thomas to figure out the complex balance between short grassland, a single species of red ant and the large blue butterfly. The reason the butterflies became extinct was due to longer grassland. After rabbit numbers in the 70’s became decimated by myxomatosis and changes in human agriculture. It became apparent management of the grass was integral to the ant thriving and the caterpillar being found.
Also olny one type of red ant could be fooled by the caterpillars. Caterpillars taken by other ants in the species would soon be found out and consumed by the nest.
This balance was integral to the unknowing Myrmica Sabuleti ants finding and raising the large blue butterflies.