There were other references in antiquity to overpopulation, but the Greeks of the 6th century were suffering from it and sending out colonists to get rid of the surplus. The Cypria was written in the 6th or 7th century, so the motivation of Zeus -- which in the earlier epic, the Iliad, is also mentioned (the Trojan War was fulfilling the will of Zeus) -- may be thought of as reflecting current affairs.
Other mentions of pruning overpopulation appear in Euripides and Tertullian.
Source: L. P. Wilkinson, "Classical Approaches to Population and Family Planning," Population and Development Review Vol 4, No. 3, 1978.
