Actually, Jim is pretty correct. That fluid is called meconium and is waste fluid the butterfly built up in the chrysalis. What it no longer needs, it squirts out. The last Io Moth I released got me good! Sometimes it's colored and sometimes it isn't. At MOSI, since we keep them in boxes, people often see the meconium and think it's blood because it is often a reddish-brown color. So I actually explain this a lot. Newborn humans also expel meconium. I accidentally found that out when I Googled to learn about the butterflies and some really gross diaper pictures showed up instead.
