Can you hold a catterpillar

Answer 1

Yes you can

Generally speaking, the majority of caterpillars pose no risk. The ones with hind projections such as the horns at the tail of hawkmoth caterpillars do not sting in any way. Some caterpillars do have urticating spines that could raise water blisters if you brushed them along the inside of your arm.

but be careful while holding them Rough handling or squeezing any caterpillars might be detrimental to the caterpillars and those individuals might not form chrysalids and produce adult butterflies.