Ah, yes, I’d seen that thread before, and then forgotten. I removed subsurface scattering from the hair texture, but I also had to uncheck “From instancer” in the texture coordinate node. So that’s only required for particle hair systems that are using objects rather than just the hair strands? Anyway, it’s solved for the hair strands, thank you! I’m still having problems with the feather objects, but I’m now pretty sure it has nothing to do with the instancer, but with the feather textures or mesh. The dark lines appear where the mesh intersects with other objects, as you can see in the image I’m attaching. It’s only visible in cycles.