Cocoon on Juncus stalk

Cocoon on Juncus stalk

Observation - Cocoon on Juncus stalk - UK and Ireland. Description: There were a few of these high visibility cocoons near the top of rush stems (often wrapped around the flowers). Are they spider egg cases?

There were a few of these high visibility cocoons near the top of rush stems (often wrapped around the flowers). Are they spider egg cases?