Check under the leaves , worms, is your soil from the garden? You can purchase a powder for the soil at he garden centre

Do you have a problem with rats? Rats love peppers.

Very unlikely a rat but I live in the woods and always have mice????

Roaches might eat pepper seedlings. I know they love tomato seedlings - I used to work in a plant pathology lab and we studied tomato, and fighting hungry roaches was one of the challenges in our university greenhouse.

They are indoors and under lights? As in, in your house?

I would suspect mice if it's something small enough to be living in your house and coming out at night and big enough to chew down a half dozen plants in the evening.

If you have video capability, try setting up a camera on your plant setup and see what happens.

Don, did you take these outside for sun exposure or use garden soil for seeding? If so there may be a hitchhiking slug hiding in the bottom of your tray. best guess.

Never been outside and not slug damage I know what that looks like. It ate very little - maybe 6-8 tiny leaves - one was chewed off but not eaten. A little could have been done 2 nights ago. It also dug up, but did not eat one peanut seed.

It also dug up 2 or 3 onion seeds.

No way it is a rat. Spider? Other bug?

@Don it is probably a mouse. Rodents love peppers.

Get a game camera and leave it pointed on the peppers. Make sure that the camera is advertised to work with something as small as a mouse.

Definitely not a spider (although spider mites can be a real nuisance). Spiders are your friend (black widows, brown recluse, etc, do not apply). If there's another bug eating on your plants a spider will find it. They are not vegetarians.

<Last night something came along and nibble the first set of leaves off most of my newly emerged peppers!>

Pictures would be helpful.