A jury has seen a DVD interview in which a child claims her parents taught her how to perform sex acts when she was five years old.
The girl's parents and two men, whose names are all suppressed, are on trial in the High Court in Wellington on a total of 43 charges, including sexual and physical abuse.
In a recorded interview played to the court on Tuesday, the eldest child, who is now 13, said she could recall several occasions on which she and her siblings were told to perform sexual acts on the accused and other adults.
The girl said a caregiver later told her those acts were adult stuff.
She also recalled an occasion when she and her siblings were stripped naked, tied up and worms and spiders put in their mouths.