Yuck! Witchety grubs in pot?
This afternoon I was transferring a potted rose into a larger pot and I found and removed 7 fat grubs in the soil that fell away from the roots of the rosebush. They were about an inch long, greenish white and curled up in the fetal position. I didn't have enough new soil to wash away all the old soil so I've put the rose with its remaining soil into the larger pot with the new soil and I'm wondering what to do now.
Is it necessary to change all the soil? Or is there some substance I can drench the whole plant in? Or are these grubs harmless? I feel sick. Could someone please advise me?