Technical Abstract: The southern cattle tick, Rhipicephalus (Boophilus) microplus, the horn fly, Haematobia irritans, and the New World screwworm, Cochliomyia hominivorax, are economically important parasites of cattle throughout the world. Understanding the biology and genomics of these pests is critical to developing novel control methods. We developed EST sequence databases for these parasites and used bioinformatic analysis to identify conceptual open reading frames and assigned Gene Ontology (GO) terms to those database trascripts that had informative BlastX hits. Bioinformatic analysis showed a large fraction of the tick database entries have no clear matches in other sequenced genomes. Several putative tick G protein-coupled receptors (GPCRs) were identified that might serve as starting points to develop novel control technologies.