The problems I began to see:
catapillers hanging upside-down to become chyrsalis and never going through the transformation...they just died. Or, they partially went through the transformation. Some of my 'pillers died...no reason. I was always careful to wash the leaves (I grow my own milkweed), and did everything as I always had done. I collected them as eggs or tiny larva and kept them in individual containers. I have always had the fruit trees which are sprayed but the milkweed isn't where the spray can drift...and, it never caused a problem in the many years before (my parents grew fruit trees, too). It was very sudden that these problems occurred. I love little creatures so I just cannot watch these things.
---------- Post added at 11:15 AM ---------- Previous post was at 11:08 AM ----------
Milkweed doesn't need to flower to spread...it spreads just fine through the roots. It is probably good that it doesn't flower and go too seed...it is quite 'invasive'.
The flowers do smell wonderful, though, and attract bees and all types of butterflies. The other really great (but spreading) butterfly plant is grapefruit mint. When it blooms, the blooms are covered.