Jennie Maria Arms Sheldon, Guide to the invertebrates of the synoptic collection of the museum of the Boston Society of natural, Boston, p.453, 1905.

The case of caddies-flies are exceeding varied and ingenious litle objects. Leptocerus (PL. 1149, fig. I) builds a straight tube of sand. Limnephilus vittatus Fabr. Has a slightly curved tube of the same substance (fig. 2), while Helicopsyche makes the young or nepionic part of its case straight, while the older or ephebic portion (fig.3 ; Pl. 1150, fig.2) is coiled like a snail shell. Fritz Muller says, that «  when preserved in adult specimens the oldest portion ( in reality the young shell) peeps out from the top of the heliciform case like a little chemney . »

Jennie Maria Arms Sheldon, Guide to the invertebrates of the synoptic collection of the museum of the Boston Society of natural, Boston, p.453, 1905.