Differential responses of adult Calliphora vicina to dry bloodstains on porous versus non-porous surface materials

•Flies modified dried bloodstains through physical disruption and feeding activity.•Stains on non-porous and smooth surfaces were mostly frequently altered by flies.•Fly activity typically yielded partial, perimeter and skeletal stains.•Flies avoided dried stains on rough, uneven surfaces.•Younger flies were more likely than older to physically modify bloodstains.