Grub Control Summer Lawn Care- Lawn Care Part VII

If you asked me to name one lawn problem that have homeowners tearing out their hair and their turf over – it would be grubs. Once grubs start damaging your lawn it is a complicated problem to work your way out of. But I am here to help!

Beetles feeding at night.

First, what are grubs? Grubs are the larval stage of scarab beetles. These can include June Bug, Japanese Beetle, European Chafer and the Asiatic Beetle. The best way to know which beetles you have is to find the beetles on your property, as they are harder to distinguish during the larval stage.  Some like to munch on flowers and herbs at night and in the morning you can see the damage they have inflicted. (see photo at right)

It is best to figure out the type of beetle larvae on your lawn in order to treat them, but in the meantime, there are some things you can do to keep grub damage at bay. 

  1. Don’t water during adult beetle activity. Why? Female beetles are looking to lay their eggs in a healthy, rich, moist environment. Adult scarab beetles tend to lay their eggs during July and August. Watering your lawn during this time attracts the females to your property. Watering now, means the conditions are ideal for next year’s grubs to thrive.
  2. Continue to mow high (am I starting to sound like a broken record?). Allowing the grass to grow at three inches or more shades your soil surface and allows the plant to make deeper roots.Longer and deeper roots will help your lawn survive damage from grubs and will make it more drought tolerant so you don’t need to water during adult beetle mating season.
  3. Don’t use beetle traps. Why not? Beetle traps also attract egg laying females to your property that can get distracted and end up laying their eggs nearby. If you are going to use beetle traps, its best to use them on a larger scale (i.e. see if your neighbors will use them too).

Once the adult beetles lay their eggs, you can apply beneficial nematodes to help control the grub population.  The best time to apply nematodes is in late summer and early fall. Wait until there are a few moist days in a row and apply the nematodes in the evening and water them into your lawn as directed on the package label.  Nematodes are parasitic and will tunnel into the bodies of grubs and destroy them from the inside out. Nematodes are another tool in the organic gardener’s tool box. They are native, occur naturally in soil, and are found to persist for years in the soil after one application. From school grounds to agricultural fields, nematodes have helped reduce the need for pesticides. For more information about nematodes, visit this UConn Fact Sheet.

So, keep your eyes open for beetles on your property and grub damage on your lawn.  And ask at your garden center if they sell the nematodes so you are ready in the late summer to apply them if you have a grub problem.  Email me with any questions.