Butterflies released in Finland contained parasitic wasps – with more wasps inside

A Glanville fritillary. This butterfly somehow seems to recover from isolated population crashes, say researchers. Photograph: Peter Eeles/Butterfly Conservati/PA

A Glanville fritillary. This butterfly somehow seems to recover from isolated population crashes, say researchers. Photograph: Peter Eeles/Butterfly Conservati/PA

source https://www.theguardian.com/environment/2021/sep/14/butterflies-finland-parasitic-wasps