Observations by tekay

We were collecting for a butterfly house, and we collected what we thought were monarch caterpillars. When we got home, we looked closer and realised they have a yellow stripe down the side, and an extra pair of 'antenae'. When the photo was taken they are captive, but the location is set to where they were wild-caught. They are eating the same milkweed in the same place we can usually find the normal monarchs, and I saw a couple of monarchs hanging around. Could someone tell me exactly what they are?
Edit- found what they are. I've never seen them around. They must breed earlier in the season.

Came into my house. Has a stripe on the underside of the abdomen. 8 eyes, 4 posterior (2 upwards facing, 2 forward facing), 4 anterior eyes, orange chelicera. About 3.5cm with legs, 1.5 without. This male spider has been in a few fights, losing 2 legs. You can see a close up of the stump of one in picture 3. I'd really like it if someone could id to spieces.