[excerpt] On January 9, 1964, a larva of the hydrophilid beetle Tropister- nus,glaber (Herbst) was removed from an aquarium and placed in a fin- ger bowl of water along with a sprig of coontail (Ceratop7tyllum demer- sum Linnaeus). The plant provided support for the larva to reach the water's surface. By accident rather than design it harbored the snail Physa sayii (Tappan), individuals of which were clinging to its leaves
Willson, Ronald B.
"Interference of the Snail Physa Sayii with Equilibrium in Tropisternus Glaber (Coleoptera: Hydrophilidae),"
The Great Lakes Entomologist: Vol. 1
, Article 2.
Available at: http://scholar.valpo.edu/tgle/vol1/iss1/2