found crawling low in grasses (near the surface of the ground) in a bramble of Red Raspberry and Goldenrod, so I'm not sure of the host plant.

For what it's worth, I've had several encounters with Pero caterpillars associated with goldenrod and/or aster in old-field habitat in Minnesota. The ones I sweep-netted at night fed on both and eclosed as clear Pero species adults, but I'm still not sure which species. Evidently either Pero host plants are considerably under-reported, or (just maybe) there is/are undescribed Pero species. Despite all this lack of clarity, I strongly suspect your caterpillar is a Pero based on the strongly cleft head and the overall striped markings which much resemble those I have photographed and reared. I do have voucher specimens which perhaps merit DNA analysis.

much for taking the time to share these observations and for drawing my attention to the morphological features that I should be paying attention to when identifying Pero caterpillars. Your help is greatly appreciated Jim.