A misnomer if there ever was one: I don't know of a single species that merits the epither "weed."
Milkweed plants harbor their own unique insect fauna including bugs, flies, beetles, wasps, bees,
ants and aphids, and especially butterflies, most notably the Monarch.
Our local species is the Narrow-leaved Milkweed, Asclepius fascicularus. The family also includes Indian Hemp,
Apocynum cannabinum, formerly widespread but known to occur in a few places in Santa Clara County.