Servius on Virgil, Eclogue 10.1
Gallus, ante omnes primus Aegypti praefectus, fuit poeta eximius; nam et Euphorionem, ut supra diximus, transtulit in latinum sermonem, et amorum suorum de Cytheride scripsit libros quattuor. Hic primo in amicitiis Augusti Caesaris fuit: postea cum uenisset in suspicionem, quod contra eum coniuraret, occisus est. Fuit autem amicus Vergilii adeo, ut quartus georgicorum a medio usque ad finem eius laudes teneret: quas postea iubente Augusto in Aristaei fabulam commutauit.
Gallus, the first prefect of Egypt, was an outstanding poet; for he translated Euphorion into Latin, as we said above, and also wrote four books of love poems about Cytheris. He was at first a friend of Augustus Caesar: later on, when he fell under suspicion of conspiring against him, he was sentenced to death. He was also a friend of Virgil, such that the fourth book of Georgics contained his praises from the middle to the end: Virgil subsequently replaced this passage with the tale of Aristaeus at the bidding of Augustus.