After the caterpillars have made their chrysalis and they are firm/dry, the silk webbing can be scrapped away from the plastic and used to pin them on an emerging board. This is where they will become butterflies. It needs to be at an angle to allow the newly emerged butterfly to hang free and the wings to expand and harden.
You see in this picture of Monarchs I have glued them to fabric (not a good idea. a pin is safer and easier). The green chrysalis is the normal color, but the day before emerging they turn black and the wing color is visible. That is because the outer shell of the chrysalis is clear. The butterfly will use the liquid in it's abdomen to expand the wings then the excess fluid is expressed. The tiny crumpled wings expand and harden. When it is able to fly, the butterfly won't nectar right away; it is more concerned in finding shelter and resting.
