Frangipani and the monarch butterfly

The last two days a monarch butterfly has been laying eggs on the frangipani tree. I have never seen that before. I have also noticed two small caterpillars on two of the leaves. They don't eat those leaves, or do they?

Karen says:
I did not see any information about monarch butterflies using the frangipani as a host plant, but it was interesting to me that the plant has a white milky, poisonous sap just like milkweed. Check out the frangipani caterpillar.