Two complete mitogenomes of the stem borers, Calameuta filiformis and Calameuta idolon, and the complete A + T-rich region of Trachelus iudaicus (Hymenoptera: Cephidae), are reported. The mitogenomes of these species are the longest reported from hymenopterans to date. A remarkable increase in length of the A + T-rich region, the longest for Hymenoptera, was found and compared across the tribe Cephini. The presence of the tRNA- and rRNA-like sequences were reported in the A + T-rich region of sawflies and they were suggested to play a role in replication and/or transcription. The long and short tandem repeats were orderly located in both sides of the A + T-rich region producing stable secondary structures. We suggest that the short tandem repeats are likely to function as a replication fork barrier. (c) 2015 Elsevier B.V. All rights reserved.