Kate Harvey  & E. J.  Lay,  Nature Class Pictures, Londres, MacMillan, 1944, p. 241

They hatch into minute larvae wich begin to construct a case by attaching bits of sand, stick, leaf, etc., to the body, glueing them together with a secretion of filk produced by salivary glands below the mouth. Some of the larvae make their case of two oval pieces of leaf stuck together, so that it is quite flate. Others makes a raft by sticking on two or three pieces of twig much longer than the tube. Many of the cases have a rough irreggular exterior, but tne interior of all is lined with silk.