We describe here the first systematic work to discover insect genes involved in food breakdown using a cDNA library enriched for gut-expressed transcripts from Callosobruchus maculatus. A total of 1056 clones were screened for cDNA insert-containing plasmids, and 503 nonredundant open reading frames were discovered. Twenty-three inferred genes potentially involved in digestive processes in cowpea weevil were identified, including proteinases and amylases. The predicted catalytic sites were identified in the inferred cysteine and aspartic acid proteinases, and in alpha-amylases. Transcriptome analysis of the cowpea bruchid will potentially permit gene discovery in other beetles, an insect order of major economic and ecological importance that is poorly represented in genomic databases.