Prickly Pear: Down to Bones

I was fascinated by the net-like "skeleton" of this prickly pear. Invasive cactus moths are taking quite a toll on our native prickly pears and we have seen many chewed, dying and dead prickly pears. But I had not noticed the skeleton forms left behind when all the thorns and flesh are gone.  I sent an email to a person who studies them to learn more but there was not a reply.