what should he do if its russets .....
...... I don't want to freak Ken out.... Ken don't freak at this answer.... You may not even have this pest. If you find that you indeed have them, freak out then.
My indoor garden was largely ruined by the russets, had to trash over half the harvest. Anything not directly under lights at the top of the canopy was eaten to death- no resin production at all. Then in many of the good looking buds, the dead mites+ mite waste molded out a fair amount of the salvaged product. I made oil from it so I could salvage it- the Pyrex had a layer of mites on it between the oil- whereby the slab of oil kind of slid along the surface of the Pyrex once it hardened. So disgusting. I then destroyed all my vegging plants instead of using miticides, for reasons I'll explain.
Outdoor looked far healthier through the season. Produced big fat buds- with no resin. Out of 6 plants taller than me I harvested about a half pound that looked at least salvageable- made bho from it and got about 3 grams.
Pitiful.
The rest was trashed- not even fit for compost IMO.
@
lino mentioned how CO Native Americans would burn their hemp when it displayed those signs- someone else already posted the link to that thread. I was concerned about diseases vectored by the mites as well, so I just trashed everything from that season. It was a big hit but better than having it spread to another season, or a friend for that matter.
You can be sure my standards and practices for taking in new plants was wholly modified after that incident.