I like to bring in every egg I can find, too, but we recently had a disastrous attack by ants- I had a stalk of milkweed on my porch with a bunch of 1st and 2nd instar cats on it, but I left the stalk leaning against the screen porch wall. In the morning I found thousands of little ants swarming up the wall and onto the milkweed, and each baby cat had about 25-50 ants attacking, maybe more. Some of the ants were dragging away the poor cats! Others seemed to be all shriveled up and sucked dry. I managed to save some of them, it seemed like the ants mainly attacked the immobile ones that were preparing to molt. Needless to say, I won't be leaving any babies out on the porch from now on!
ps on a lot of my plants outside, I find the little ring of feeding damage from a first instar cat, but no sign of any older ones- so they seem to be lost as eggs or first instar mainly.
Waystations 15 & 629