Son of Mothrakk is likely a reference to the creature Mothra of Godzilla fame who appears in a moth like form. Mothra was a spirit that would lay an egg and die at its hatching to be reborn into the new larvae. In cases where Mothra defeated Godzilla, Mothra had been reborn into this second incarnation before defeating Godzilla.
It is also decended of Mothrakk, a boss from the original Borderlands. Mothrakk itself was a reference to Mothra from Godzilla.