Trombidium breei
At Hatch Hill today most of the Marbled White butterflies (Melanargia calathea) were covered in red mites (Trombidium breei). These parasitic attach to the butterflies bodies to feed from their blood. They really standout against the black and white butterflies. Apparently in small number they cause no harm, but can kill in large numbers. Not sure what counts as large numbers.
Marbled White (Melanargia galathea)
Marbled White (Melanargia galathea)
