This plant had both an egg and an already-hatched caterpillar. Hopefully, as it grows, it will find not only sufficient milkweed, but also abundant nectar resources for its adult life.
ENPO170427_D007
The Prairie Ecologist
Essays, photos, and discussion about prairie ecology, restoration, and management
The Prairie Ecologist 
the white spot could be from a parasitoid. Tachnid fly maybe?
Multiple eggs in close proximity do not always result in multiple larva. Normally, the first thing a newly hatched larva (it hatches by eating its way out of the shell) does is eat its empty shell. Then it starts to roam around a little. If another egg is in the vicinity, it will eat that before going on to eat milkweed. The typical estimate for a Monarch egg to reach adulthood is 3%. Too many predators, parasites and/or ailments.
I’m presently reading “The Life in your
Garden”, 2016 by Reeser Manley and
Marjorie Peronto. They write about a tachinid fly, Isocheta aldrichi imported
from Asia in 1922 and released to combat unwanted herbivores. Specifically they show a picture of a Japanese beetle with the fly’s egg on its thorax.. looks like the one on the caterpillar . Rick C.