Liebers, Landaus, Bodeks Garni bags should not be used.
עיין במשבצות זהב יו"ד סימן פ"ד לג
All of their Hashgochas were warned the insects not to go through the holes.
Bodeks, Landau's, Liebers "Garni bag's" should not be used;
holes are too large,
bags too small, etc adult thrip insects go right through.
It's very visible to the plain eye, you don't need a loop to see it.