The source of the sugar
residues for chitin synthesis can be traced to fat
body glycogen, which is acted upon by glycogen
phosphorylase. Glucose-1-P produced by this reaction
is converted to trehalose, which is released into
the hemolymph. Trehalose, the extracellular source
of sugar in many insects, is acted upon by a trehalase,
which is widely distributed in insect tissues
including the epidermis and gut to yield intracellular
glucose (Becker et al., 1996)