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With a life's experience of teaching field studies in the Forest of Dean, Brian Cave explores the ecology of rural France. More Info

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An English Naturalist in France

Some thoughts on caterpillars

April 27, 2015

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Spotted Fritillary caterpillar

   This caterpillar was photographed on April 26th chewing happily on a leaf of the common plantain (Plantago lanceolata), growing in a pasture  in South Central France.   It is the larva of the spotted fritillary.  
It brings to mind the discussion on clandestine evolution familiar to all students of nature.  The caterpillars are all so different in appearance from the adult that the ignorant observer would never consider that they could possibly be the same species.
This specimen was only 15 mm long, about half its final size before it changes into a pupa and then the adult.
It is covered in conical protuberances, two rows of which are orange red, the rest being white.  All the cones have fine spines projecting from the sides and the apex.    The creature feeds exclusively, it seems, on plantain leaves.  The caterpillar has no sex, yet when it becomes an adult it will display either a male or a female gender

I try to imagine the influences of natural selection which brings about the ‘clandestine evolution’ of the caterpillar compared with the adult.  That is difficult indeed.  One needs to grasp which predators might attack it during all the millennia of its history.  How and why the adult lays its eggs on such particular species or why the caterpillar only eats that plant – or does it?

One really wonders at and is astonished by the complexity of the whole detail of nature. 


by Brian Cave. Find out more about Brian Cave here.