Enzyme changes during development of holo- and hemi-metabolic insects.

-l. Several carbohydrate metabolizing enzymes were examined spectrophotometrically and electrophoretically in four life stages of the holometabolic fruit fly, Drosophila pseudoobscura, and in three life stages of the hemimetabolic pea aphid, Acyrthosiphon pisum. 2. Drosophila pupae exhibit significantly lower enzyme activities than third instar larvae. Most enzymes recover to larval levels or higher in adults, but some continue to decrease following eclosion. 3. Enzyme activities remain relatively unchanged during development of Acyrthosiphon. 4. The same isozymic forms of each enzyme are usually represented in all life stages of Drosophila, and in all life stages of Acyrthosiphon. 5. Enzyme levels parallel the distinct morphological and physiological changes characterizing development of representative holoand hemi-metabolic insects.