Grubs in Home Lawns

Grubs in Home Lawns

It’s September and that means only one thing when we talk about lawn insects – grubs! It’s important to understand the lifecycle of these insidious lawn pests. The following gives a timeline of the lifecycle of the Japanese beetle, an insect easily recognized by many gardeners.



Grubs are deep in the soil.


Grubs come up near surface to feed on turf roots.


Grubs feed, then prepare to pupate in the soil.


Adult beetles emerge from ground and feed on plant leaves.


Beetles mate and lay eggs in ground, preferably in lawns.


Eggs hatch, then young grubs feed on lawn roots.


Grubs continue to feed and grow rapidly if the soil stays warm.


Grubs are mostly full grown. As the soil cools, they burrow into the soil for the winter months.

In September and October, young grubs should be in the upper root zone area of the lawn, actively feeding on the roots of your lawn. If found, the sooner you treat with a labeled insecticide, the better! The younger the grub, the more effective the treatment will be. Read and follow the label directions to a tee. If left untreated, grubs will continue to feed for the next 4-6 weeks (or longer if we have a warm, extended fall) before they dig deeper into the soil to spend the winter months. They’ll begin to surface again next spring, and resume feeding.  The only difference, older grubs are much more difficult to control than those found in your lawn now. To the point – treat now when grubs are young and most vulnerable to insecticides.


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