I want to get some beneficial nematodes, primarily for control of fleas and Japanese beetles. In looking over the various websites that sell them, I see wildly different recommendations for numbers and coverage, anywhere from 5million/300sqft (gardensalive.com) to 1million/2000sqft (thebeneficialinsectco.com). If I use gardensalive's recommendation, it would cost me about $600 to treat my lawn. If I use thebeneficialinsectco's numbers and buy from them, it would cost me about $90.
Is there any reason for this massive difference? Is it based in reality, or just marketing hype?