On average it takes 3 years of applying nematodes every Spring & Fall to push them out of your lawn. After that is done you will have to make a nematode application as a part of your Fall maintenance. When grubs show up in a neighbourhood the always stay because some people on your street will not use nematodes because they don’t believe they work or don’t have the time or money to do anything and some just don’t care. Without a doubt on a windy day, a Japanese Beetle will end up in your backyard and start to lay some eggs again, this is why you mustapply nematodes in the Fall to prevent the cycle of damage from starting over again.