In insects, the enzyme trehalase plays a crucial role in energy metabolism, chitin synthesis and possibly during plant–insect interactions. We have characterized a soluble trehalase gene (Tre-1) from cDNA of Aphis glycines, a serious migratory pest of soybean. The full-length cDNA of Tre-1 in A. glycines (AyTre-1) was 2550 bp long with an open reading frame of 1770 bp that encoded for a 589 amino acid residues protein. Sequence assessment and phylogenetic analysis of the putative protein suggested that the selected cDNA belongs to soluble trehalase group. Quantitative PCR (qPCR) analysis in different tissues and developmental stages revealed peak mRNA levels of AyTre-1 in the gut (compared with other tissues assayed) and highest expression in the second instar compared with the other developmental stages assayed. Interestingly, a significantly increased expression of AyTre-1 (1.9-fold, P < 0.05) was observed in the alate morphs compared with that in apterate morphs. However, there was no significant difference in AyTre-1 expression in A. glycines-nymphs fed with resistant and susceptible plants. Expression patterns identified in this study provide a platform to investigate the role of AyTre-1 in physiological activities such as flight and feeding in A. glycines. The characterization of soluble trehalase gene may help to develop novel strategies to manage A. glycines using trehalase inhibitors and using RNA interference for knock-down of AyTre-1 expression.