Although Myllocerus maculatus was suggested, and these have root grubs, and the symptoms were typical of this insect, other members said that it was unlikely to be this. Myllocerus is a weevil, and this is a member of the Chrysomelidae. A response from the Australian Museum said that its a eumolpine, but there are dozens of genera in this region. Many eumolpines are polyphagous, so just because its a mango doesn’t mean its a pest from SE Asia.This was confirmed by a note from CSIRO.