One of my customers has a problem, his plants have no roots.

An all to come problem, you are waiting for your plants to burst into growth an into flower, then nothing. You go and investigate and the plant has no roots and it is loose in the pot. Just what can be the problem.

Not a very healthy looking plant

The plant has no roots, but what are those grubs in the soil.

Its the dreaded vine weevil, typical illustration showing the little grubs that have devoured the roots, and are waiting to mature into larvae, there next stage in there life cycle, then onto being a weevil with legs.