Question
Northern Indiana   When is the best time of year to apply milky spore to my lawn in order to control the Japanese beetle?

Answer
I have no experience with the product but I found some useful information at the following site

http://www.ces.ncsu.edu/gaston/Pests/japbeet.html#spore
Here is a direct quote.

"One product in a little bit of a different category is Milky Spore. Milky Spore is a naturally occurring bacteria that is effective in controlling Japanese beetle grubs only. This product is best applied on an overcast day in late September or early October to a soil that has a pH level between 6 and 7. The results are not as fast as the chemical insecticides, but the effects last many years. Once established the milky spore will naturally spread to untreated areas. As a last point, studies have indicated that traps for Japanese beetle adults have no real impact or the populations in the area and may draw in others from as much as a 1/4 mile away."