The Aretalogy of Karpocrate in Chalcis #4:
Bakchoi and Bakchai? The Child Prophets of Apis?
Βάχχοις καὶ Βάχχαις ἀεὶ συνθιασώτης εἰμί
I am always the partner-in-the-thiasos with the Bakchoi and the Bakchai
(RICIS, 104/0206, 8)
The Bakchoi and Bakchai were in fact the child ministers of a rejuvenated religion centered on the sacred child Dionysos. Their emergence reflects the Hellenistic era's characteristic sentimental piety toward child gods, during which the traditional image of Dionysos was deliberately rejuvenated, especially in Alexandria and Ptolemaic Egypt. These youthful attendants, of both sexes, ritually served the young god in processions. They often engaging in play with sacred animals or appearing winged, that's why they were often mistakenly identified as Eros figures.
source: J.-Ph. Lauer et Ch. Picard, Les statues ptolémaïques du Sarapieion de Memphis
When the successor is found it is led by 100 priests to Memphis. It has a pair of shrines, which they call its bed-chambers, that supply the nations with auguries: when it enters one this is a joyful sign, but in the other one it portends terrible events. It gives answers to private individuals by taking food out of the hand of those who consult it; it turned away from the hand of Germanicus Caesar, who was made away with not long after. Usually living in retirement, when it sallies forth into assemblies it proceeds with lictors to clear the way, and companies of boys escort it singing a song in its honour; it seems to understand, and to desire to be worshipped. These companies are suddenly seized with frenzy and chant prophecies of future events.
(Pliny, Natural History, 8.71)
Apis, it seems, is in effect a good prophet: he to be sure never sets girls or elderly women on tripods, never fills them with some sanctified draught, but a man prays to this god, and children without, who are playing and dancing to the music of pipes, become inspired and proclaim in time with the music the actual response of the god, so that what they say is more true than what occurred by the Sagras.
(Aelianus, On the Characteristics of Animals, 11.10)
But Isis wandered everywhere at her wits' end; no one whom she approached did she fail to address, and even when she met some little children she asked them about the chest. As it happened, they had seen it, and they told her the mouth of the river through which the friends of Typhon had launched the coffin into the sea. Wherefore the Egyptians think that little children possess the power of prophecy, and they try to divine the future from the portents which they find in children's words, especially when children are playing about in holy places and crying out whatever chances to come into their minds.
(Plutarch, Isis and Osiris, 14)
Pittacus raising his staff, the weapon of his old age, said "Look ! they will tell you all you need know"-The boys at the broad cross-roads were whipping their swift tops-"Go after them," he said, and the man went and stood close to them, and they were saying, "Drive the way that suits you." (Greek Anthology, 7.89)