Eggs
Neonate
First instar
Second instar
Third instar
Fourth instar
Fifth instar
Pupa from above is very cryptic - resembles lichen-covered branch stub
Pupa from underside shows wings
Fresh adult Blue Metalmark, dorsal view
Fresh adult Blue Metalmark, ventral view
According to a friend who is an expert in raising caterpillars, Blue Metalmarks are one of the most difficult species to raise. He resorted to rearing them on green beans from the grocery store (warning if you try this: make sure the beans are truly organic, as any pesticide residue may prove fatal to the larvae). I would agree that they are difficult: he has given me eggs on a couple of occasions, but the caterpillars never got beyond the second instar. Finally, in 2020 I found two caterpillars on Texas Ebony (Chloroleucon ebano) that made it through to pupation.
The caterpillars were kept in ventilated containers and misted twice a day (my practice for tropical species). One of the prime difficulties in feeding them was finding tender Ebony leaves and keeping them fresh. Even though I had a couple of potted Ebonies that I grew from seed for the purpose, there was little of the growth that the caterpillars liked. Fortunately, I had some bean plants (as a potential skipper host, of course) with a couple of beans on them, and I was able to offer the green beans without concern for pesticides. But the caterpillars were growing very slowly, and I was concerned about the food supply. I was staring at the Ebony in my yard when it occurred to me to try offering the Ebony beans: the tree was covered with immature beans. These were readily accepted. Interestingly, when I made all three foods available, the caterpillars ate of all three. It is possible the Ebony beans provide nutrition the leaves lack, and vice versa.
The changes in the caterpillars as they matured were interesting. The first instar has very long setae (hairs) growing on its back. In later instars, these setae are very short. The third instar gained markings on its back that that reminded me of railroad tracks. The fourth instar gradually became green; the final instar, especially when freshly molted, looked like it was wearing a camouflage jacket. The setae on the side help disguise the lines of the body, so a caterpillar resting on a greenish Ebony branch would be practically invisible.
The caterpillars when prepupal seemed to hunch up and shrink. The chrysalis was the real surprise. Instead of being snug to the surface, it jutted out, and from above it looked just like a branch stub.