Life cycle of the Cloudless Sulphur

Here is a male courting a female cloudless sulphur in the meadow.

The female has been laying egs on the wild senna (cassia hebecarpa).

Here you can see one of the eggs on a senna leaf.

And here is the caterpillar on the senna pod.
From "Butterflies of the East Coast" by Cech and Tudor, "It ranges in summer from Pataglonia to southern Canada.  ... Why large numbers fly far north in fall, never to return, is a mystery."