looks like it to me , about the size and color

I forgot , it could also be a Milbert's Tortoiseshell ,,They will copy traits , of each other , plant tannins ? weather ? I dunno

Red admirals always have a dashed line, creamy colored, on their side, and you rarely ever see them, because they're nearly always in their nest. It doesn't look like that one has come out to make another nest. That caterpillar looks more like a question mark, but there are commas and tortoiseshells (closely related to QMs) up North that it could be.

Here's a picture of an RA cat from last year. You can see the creamy, dashed line, and you can see how the cat was quickly making a new nest. They always start the new nest at the top of the leaf, near the stem -

Sherry

I looked through my old pictures and found this picture of question mark caterpillars -

Sherry

I don't know if this is diagnostic, but when I look closely at the pictures of question mark caterpillars, the little bristles always have multiple prongs. The red admirals have a simpler spike.

When I went out this morning, one of the caterpillars had migrated underneath the paper towel at the bottom of the cage. Do you think he is getting ready to pupate? He and his brother had pretty much eaten the entire stalk of nettle, so I worried he was out of food. I put in a fresh stem for the remaining caterpillar.

That tortoiseshell is a really pretty butterfly! Unfortunately, it doesn't appear to occur in New Jersey, so I think we can rule that one out.

Caterpillars sometimes go under the paper towel to pupate, so that's probably what it's doing. After it's made its chrysalis, you can cut a big area of the paper towel off that the chrysalis is on and put it on the topside of the bottom of the cage, if you want. I usually fold some of the extra paper towel over the chrysalis, so it'll still feel protected. If it makes its chrysalis under the paper towel and you leave it there, it might get hung up when it emerges and break some wings trying to get out.

Sherry

Nice to see these pictures,I have RAs as well as QMs here,

(or Commas?)

I have seen the little caterpillars,possibly,without knowing whose

They were.

DD

I have had lighter colored Red Admirals. Not sure if I took pics though. Yours looks like mine did. Post the chrysalis--that will tell for sure. :) (Bernergrrl from old GW)

They finally emerged a couple of days ago. Not the best picture, but he didn't want to hold still.

Just gorgeous! The coloring is to die for on a newly emerged RA!

Sherry