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Timely Tip – Grub Damage

White grubs can devastate your lawn

White grubs are small, plump, white beetle larvae which voraciously feed on grass roots. They live below the soil surface and actually chew off the roots of the grass, limiting the lawn’s ability to take up water and causing symptoms of dryness.  Large areas of your lawn can dry out and die, necessitating costly repairs.

Diagnosing white grub damage

In southeastern Pennsylvania damage is not usually seen in spring and early summer, but rather from late August through October when populations attain the 12-15 grubs per square foot necessary to do damage.  Grub damage can be easily distinguished from drought, disease and other insect damage.  The feeding grubs sever the root system, allowing the dead lawn areas to be easily rolled up like a carpet.  Other indicators of possible grub infestation include: animals like skunks and raccoons digging up the lawn and birds feeding on grubs, leaving pencil-sized holes.  

Controlling White Grubs
The best control is achieved with a preventative application of Merit grub preventer applied late May-July.  While 100% control is not achieved, the Merit prevents grub populations from reaching damaging levels.  If a preventative such as Merit was not applied and grub feeding is identified in late August through October, a post grub control must be applied.  It is very important that the post grub control be watered in with ½” – 1” of water to move the product as quickly as possible to the root zone, where grubs are active.  Expect the product to control 50-80% of the population, which is sufficient to curtail damage.  Additional damage may become evident up to 2 weeks after application of the post control, as grass dries out from damage caused prior to the application taking effect.  You will not get results until irrigation or rain move the post grub control to the root zone, where grubs feed.