Thank you for sending the images of what you suspect to be blister beetles.
For several reasons, I’ve requested an entomologist’s assistance. While we wait for a response, and if you still have the insects, please send me several additional well-focused images.
If you prefer not to wait for the entomologist’s response, you could take the insects to the Lane County Extension Service Office where the Master Gardeners can help you. The office is at 996 Jefferson Street, Eugene, OR 97402. Hours Monday through Thursday 10 am to 1 pm, and 2 to 5 pm.
I did a Google search "Images of dead blister beetles found in alphalpha hay" and what saw on a chart of The Life Cycle Of The Blister Beetle looked very similar. These larva like critters are throughout the bale. SB