IMHO it looks like leaf streak.
Here's the link from AHS with the photos
http://www.daylilies.org/ahs_d...
I don't think earwigs would do that. The adults just eat the flowers, the young will eat the foliage but leave holes in them. I have had earwigs bad at the last place I lived, but they never bothered the daylilies. I sprayed for them when they started coming inside the house. I used the Bayer Advanced Complete Insect Killer for soil and turf; I spray the soil and the plants with it. It's a systemic that lasts up to 30 days. If the earwigs are not causing any damage I would just leave them alone because they are mostly considered a beneficial insect.