A true -amylase was demonstrated from crude and partially purified extracts from whole carcasses of sweetpotato whiteflies (SPW) (Bemisia tabaci Genn.). All nymphal instars and adult SPW were found to have active -amylase, including newly enclosed crawlers that had not yet fed on plant materials. Protein-specific activities were greatest in 1st instars and decreased with age up to the "pupal" stage with a very slight increase in activity in adults. However, activity per individual did not differ substantially as a function of age. The -amylase had an apparent molecular weight of about 70 KD and an isoelectric point of 6.32. The enzyme activity was severely inhibited by EDTA and activated by NaCl and KNO₃. CaCl₂ also strongly enhanced activity. -Amylase activity was greatest at pH 7.0, but there was considerable activity at pH's below 7.0. Implications are discussed of the meaning of -amylase activity in an insect thought to be a phloem feeder.