When to Use a Grub Killer

Grubs are the adolescent form of many beetles. There are two major factors in treating grubs: Identifying grubs is important because there are other things that can cause lawn damage that looks similar to the damage caused by grubs. Secondly, it is important to know when to apply the grub treatment, as this will have a large effect on grub killer effectiveness.

The first thing to do when deciding on using grub killer is to determine that the problem is actually grubs. While sporadic brown patches of lawn are good indicators, other things can cause this to happen. When grubs attack the roots, they kill the lawn, but they also cause it to be easily rolled up (similar to carpet). To be certain of a grub problem, roll up the lawn and see if any grubs are hanging from the roots or in the soil. Grubs have long bodies, similar to caterpillars. To distinguish grubs from caterpillars, check the legs. Grubs have six legs grouped close to their heads, while caterpillars will have many more running all along their bodies.

Grubs tend to burrow into the ground for the winter, sinking under the permafrost, so it is best to use grub killer in late summer or early fall. They will still be feeding at this time, and are still relatively small. Grub treatment can be applied in the spring, but they won't be feeding right away early on, so treatment may not be as effective.

Pretty much any chemical grub killer will both kill existing grubs and prevent grub growth and will help to maintain a grub problem. If you are worried about toxicity, there is an alternative that works for certain types of grubs. Spreading milky spore over your lawn rather than a chemical-based grub killer (milky spore is a fungus) is effective for killing japanese beetles and their grubs. While it does work for several other types, it is important to keep in mind it will not work for every type of grub.