During metamorphosis, the insect hemolymph transforms into a reservoir for a group of physiologically and developmentally important proteins. Two different hexamerin-like cDNAs (Hexa-1 and Hexa-2) identified from R. flavipes cDNA macro-arrays were isolated and sequenced. The complete cDNA of Hexa-1 consists of a 2223 nucleotide ORF encoding a protein with 740 amino acid residues, whereas Hexa-2 has a 2205 nucleotide ORF encoding a protein with 734 amino acid residues. Hexa-1 and Hexa-2 share 56.6% nucleotide sequence identity and 45.4% deduced amino acid sequence identify. A 20-amino acid signal peptide, an isoelectric focusing point of 6.73, and a molecular mass of 87.7 kDa are predicted for the Hexa-1 protein, while a 18-amino acid signal peptide, an isoelectric focusing point of 6.49, and a molecular mass of 86.9 kDa are predicted for the Hexa-2. Both genes have high content of aromatic amino acids (16% and 19.5% for Hexa-1 and Hexa-2, respectively), and conserved signature domains. Expression of mRNA for Hexa-1 and Hexa-2 among castes and developmental stages is slightly different, and suggests a role in caste differentiation. Phylogenetic analyses based on peptide sequences validate our conclusion that both Hexa-1 and Hexa-2 are members of the arylphorin subfamily of the hexamerins.