Technical Abstract: The brown citrus aphid (BrCA), Toxoptera citricida (Kirkaldy), is considered the primary vector of citrus tristeza virus (CTV), a severe pathogen which causes losses to citrus industries worldwide. The alate (winged) form of the BrCA can readily fly long distances with the wind, thus spreading CTV throughout and across citrus growing regions. To better understand the biology of the BrCA and the emergence of genes expressed during wing development, we undertook a large-scale sequencing project of cDNA clones from alate BrCA. Sequencing projects from other insects have provided answers to biological questions relating to development and physiology. Currently there are relatively few genes identified from aphids. However, important morphogenetic processes are exclusively associated with aphids such as parthenogenetic development and sap feeding insect metabolism. We have produced the first public data set of expressed genes from the brown citrus aphid, Toxoptera citricida (Kirkaldy). The cDNA library was derived from alate adults due to their significance in spreading viruses (e.g., CTV). Over 5180 cDNA clones were sequenced, resulting in 4263 high-quality BrCA ESTs. Contig alignment of these ESTs resulted in 2124 total assembled sequences, including both contiguous sequences and singlets. Approximately 33% of the genes identified have no significant match to currently described genes, suggesting that sequencing projects still provide new information to the scientific community. Sequences returning matches with an E-value of = -10 using BLASTX, BLASTN, or TBLASTX were annotated based on their putative molecular function and biological process using the Gene Ontology classification system. This data will aid research efforts in the identification of important genes within insects, specifically aphids and other sap feeding insects within the Order Hemiptera.