They actually can bite, or pinch, whatever. I once took out a pair of socks and put them on. Shortly, I experienced an uncomfortable feeling on the top of my foot. Thought I had laced my shoes too tight, so adjusted. It happened again. I finally took my sock off and there was a live stink bug who had found a warm place to hide in my sock! There were actually two in there and I had a mark where he had been pinching me. Didn't break the skin, but it hurt a bit anyway.
Dale