By Stan Moore
Michigan State University Extension
Over the course of the last month or two, we have being hearing from a number of homeowners that they are watching their lawns being destroyed by some creature(s). There are several possible culprits, but there is likely one culprit at the root of the problem, grubs.
Skunks, raccoons, possums, badgers and even birds may be digging/pulling up the lawn as well, however. The first four work mostly at night, so it is much more difficult to determine which is doing the damage. Your control options will vary greatly by the area that you live in and what your personal preferences are. One deterrent that I am currently employing is a motion detector light and with a little modification I can add some sound to the detection device as well. This has not eliminated the digging by raccoons (in my case), but it has dramatically reduced it.
The root of the problem is really what needs to be dealt with and at the roots (actually feeding on them), is one or more species of grubs. The three most common in our area are European Chafer, Rose Chafer and June Beetle. Japanese Beetle numbers are also increasing in some areas. Grub size ranges from a quarter to over one inch long depending on species and age. The grubs have unique arrangement of hairs on their hind ends based on their species and these patterns are useful for identification. The Department of Agriculture in Maine also has some very nice pictures of larva and adults and includes the species that are important in Michigan.
June Beetles can be more difficult to control because their life cycle and damage last two seasons. First year, smaller grubs are much easier to control. Products that control grubs when they are small are generally called “preventative” and usually contain one of two active ingredients: Imidacloprid or Chlorantraniliprole. Products containing Imidacloprid should be applied between June 1 and July 15 for best results. Products containing Chlorantraniliprole should be applied between April 15 and May 15. Again these are considered preventative. They generally are quite effective when applied and watered in properly (half inch of rain or irrigation water).
If you find yourself with large grubs this time of year, your control options are fewer and results will be less effective. These controls would be titled Curative Products and either contain Carbaryl or Trichlorfon. Research conducted by T. Davis and D.R. Smitley of Michigan State University (MSU) suggest that these will kill 20-55 percent of the grub population. More information is contained in an article titled “Home Lawn Grub Control Products 2012” by Davis and Smitley.
For more help on this topic please call the MSU Extension Lawn and Garden Hotline at 1-888-MSUE-4-MI (1-888-678-3464).