Whew, I am just learning this stuff but here’s what I learned about the life span of the monarch butterfly.
The butterfly only lives for about six weeks or so.
during a summer, this laying of eggs on the milkweed occurs, of course, once every six weeks. The final egg laying is called the fourth generation, usually late in August, early September. It is THIS generation that will migrate, eventually hibernate over the winter in Mexico or somewhere, then return to these climes, lay the first batch of eggs and the life cycle goes on.
So i’d be looking for these caterpillars, well they about all year as the above life span would indicate, but right about now is the most important.
As of now everyone of my guys is gone, I’m think to a chrysilis somewhere. The “butterfly plant” is stripped bare and they were really fat guys toward the end.
But this fourth generation is out there as they begin migrating at the end of September/early October.
In the future, build yourself a bug cage and put the plants with the caterpillers in it. They will continue to feed and morph without threat of being eaten by predators such as birds or other creepy things.............
You're actually doing them a favor.......