What are these I found on my spinach?

I found these on the underside of my spinach leaves.
I know they are cocoons of some sort, but can you tell me which pest? I am guessing they are foe not friend.




( photo / image / picture from Beeker's Garden )






( photo / image / picture from Beeker's Garden )






( photo / image / picture from Beeker's Garden )

 

I have seen them on some of my plants but have no idea what they are. Best to spray for them in case of aphids.

 

The last one is a bad one. Cabbage mothy thing. smoosh it.

 

I believe that the last foto is the chrysalis of the cabbage white butterfly (Pieris rapae).

 

Thank you, all.

I put them both on the sidewalk out near the street where the birds can get at them.