Hibernaculum: a tent or sheath made out of a leaf or other material in which a larva hides or hibernates.
"Explanation of Terms Used in Entomology" by John. B. Smith
The frogs and toads are all in their hibernaculums in the ground.
"Ways of Nature" by John Burroughs
Probably Ludlow Cave, along with the several abandoned coal mines in the county, serves as a hibernaculum for some species of bats.
"Mammals of Northwestern South Dakota" by Kenneth W. Andersen
Soil temperatures were taken in the present study only when the turtle was in a form, hibernaculum, or den.
"Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz" by John M. Legler
I back-tracked him from his faltering efforts, and where his first lusty jump showed on the thawing ground I found his hibernaculum.
"Everyday Adventures" by Samuel Scoville