While Monarchs usually disappear after their first appearance in April, they seem to reappear in July and August in the St. Louis area.
Monarchs began showing up in early July and laying eggs. I spotted their caterpillars around August 1st.
Just yesterday, August 8th, they were again laying eggs on my local milkweed. They are still laying eggs as of August 27th. This should be the last generation before they head to Mexico.
In the last six weeks, I’ve also had at least one male Monarch in the yard flying about the flowers.
The trick to attracting Monarchs is to have lots of milkweed, the more the better.
Butterfly Gardening 