In the gall the insect undergoes a metamorphosis, passing from the larva or 'worm' stage to the chrysalis or pupa stage and thence to the imago or adult stage.
(the insect; undergoes; a metamorphosis; L:In the gall) (the insect; passing; from the larva; worm' stage; to the chrysalis or pupa stage and thence)
the insect the insect
undergoes passing
a metamorphosis L:In the gall
from the larva worm' stage to the chrysalis or pupa stage and thence