One of the joys of walking around the Oa on sunny May days is the carpet of marsh fritillary larvae that are seemingly everywhere, this year at least. Last summer was a good one for the adult butterflies, and as a result plenty of their caterpillars have made it through the winter and will begin pupating very soon.
But not this one.
The marsh fritillary is notorious for its boom and bust years and one of the factors that may be responsible for this in the UK is the prevalance of two types of parasitic wasp (Cotesia melitaearum and Cotesia bignellii) which lay their eggs directly into the marsh fritillary larva. The larvae of these wasps then eat through the caterpillar before creating these tell tale cocoons that look like grains of fluffy rice.
It's the ciiiiiiiiiiiiiiircle of life.