As of November 2015, Milky Spore can be purchased through a number of retailers, including Amazon.com, Lowes.com and through the manufacturer's website, StGabrielOrganics.com. Milky Spore is a brand name and is manufactured exclusively by St. Gabriel Organics, formerly St. Gabriel Laboratories. Milky Spore consists of a naturally occurring bacterium that causes milky spore disease. This disease targets Japanese beetle grubs but is harmless to other living organisms, and it is considered a safe, effective product to treat Japanese beetle infestations.
Milky spore disease is most effective under specific conditions. Because Japanese beetle grubs are less active in cold weather, the soil in which the spores are spread should be at least 65 degrees, warm enough for the grubs to ingest the spores while actively feeding in the soil. Milky spore disease is also more effective when a large number of grubs are present in the soil, as infected grubs will help continue to spread the disease by releasing new spores as they die and their bodies decompose.
Although milky spore disease has no effect on adult Japanese beetles, targeting grubs is generally more effective than trying to eliminate adult Japanese beetles through other methods.
Milky Spore will remain active in the soil for up to 15 to 20 years, so repeated applications are usually unnecessary.