The Calamaia was a festival related to the threshing of the grain during the summer. In my previous comic Anthesteria Demeter promised Persephone to tell her about her past in Arkadia after the Calamaia (how she turned to Demeter Erinys after being raped by Poseidon and gave birth to the horse Arion. I took the liberty to place those events before Persephone was born).
If Demeter knew WHY Hades is the one god Persephone trusts to a sk about pregnancy protection, she'd be even MADDER.
Ohhhh Hekate has had enough
And I remember reading, how she was in a cave when Persephone was taken so....