The nutritional value of 30 carbohydrates, mainly mono- and oligosaccharides and sugar alcohols, was determined by longevity experiments on the Australian sheep blowfly Lucilia cuprina. Carbohydrates which maintain life for considerable periods are hydrolysed by enzymes present in the gut and salivary glands. The crop is an important site of hydrolysis of carbohydrates. The midgut and salivary glands secrete similar carbohydrases. These include two ±-glucosidases, an ±-galactosidase, and an amylase. A ²-fructofuranosidase may be present, but this requires confirmation. Field experiments indicated that the important natural sources of carbohydrates were the honeydew of coccids and psyllids and the nectar of Eucalyptus blossoms.