Amylase enzyme was extracted from both anterior part of the foregut and
posterior part of the hindgut of the fifth instar larvae of Egyptian cotton leaf worm,
Spodoptera liftoralls (Boisd.).Then it was checked using starch and mercuric chloride
as substrates. The present work shows that, activity of the enzyme depends on some
important factors; incubatIon temperature, starvation and pH number .Amylase In the
fifth instar larvae is acidic (optimum pH about 6) and the suitable Incubation
temperature is 35 te. Starvation cause, an abrupt increase in the enzyme activity for
the first four hours fonawed by a contlnious decrease of Us activity. Feeding larvae on
castor bean fresh leaves dipped In extrads of either bestachia or dumb cane leaves in
methanol and hexane, results in a significant inhibition in the activities of amylase
enzyme In all treatments.