Answer: Yes, these beetles are more than likely harmful. It is difficult to say which beetle is at work without a description, but most beetles do damage. I would throw away the soil with the beetles, wash out the container with a solution of 1 part bleach to 10 parts water, and start over with fresh soil. Check your other containers for beetles, if they are infested, then yes, I would discard the soil and start anew.
Q&A Library Searching Tips