Is it too late to apply beneficial nematodes?

To kill Rose Chafers and Jap Beetles in Z5 Michigan?

I don't think it's too late, but mine had to be watered in for 10 days to keep them viable and get working. Can you ask the vendor you are buying/bought them from? If you get them in now, they'd keep working through the season so it wouldn't be too late. I got mine down before all the storms we've had so I got 9 days of watering in. I sure hope they work! I had my lawn torn up last year by racoons and a skunk and it's now filling in again so I don't want any more critters tearing up the lawn. Good luck.

Please keep us posted on the results.
Where did you get yours from?

I bought mine from Bugological.com - I'll let you know!