lawn & garden tips > grub control

Protecting Your Investment from Grubs
White grubs are considered the number one lawn insect pest in Ontario. They have the potential to inflict serious damage to home lawns when populations reach a significant level.

White grubs are a general term used to describe the larvae stage of scarab beetles. The two main species of grubs that cause damage to lawns in Ontario are grubs from the European Chafer Beetle and the Japanese Beetle. June Beetle grubs are less common but can also inflict serious damage to lawns when they occur. European chafer and Japanese beetle grubs complete their lifecycle in one year, while June beetles take three years to complete their lifecycles.

European chafer is the most common grub species found in Ontario. These grubs normally hatch mid to late July (depending greatly on weather and soil temperatures). They begin feeding immediately and continue feeding into late fall. They over-winter as a mature grub in the soil just below the frost line and reappear early in the spring. They feed for a short time in the spring (4-6 weeks) before pupating. Following pupation they change to adults. In late June adult European Chafer Beetles emerge and begin their mating flights. Unlike adult Japanese beetles, adult European chafers do not damage trees or other landscape ornamental plants.

Healthy Lawns can Tolerate a Few Grubs
Grubs cause damage to lawns by feeding on the roots of turfgrass plants. They feed veraciously on turf roots weakening the plants and affecting their ability to take up moisture. Turf damaged by grubs often appears as scattered irregular brown patches. Damage lifts up easily like a carpet, due to the lack of roots holding it in place. Further damage to turf can occur from animals digging for grubs including raccoons, skunks, and birds. This type of damage is often more severe than the damage caused by grubs.

Healthy irrigated lawns can tolerate a few grubs per square foot without showing signs of damage. When populations reach 5-10 grubs per square foot damage can begin to appear especially if the homeowner is not keeping up with their watering practices.

An important defense against grubs and other turf damaging pests is to promote a healthy lawn. A healthy lawn is achieved through proper cultural practices; such as mowing, watering, adequate fertilization and core aeration where necessary. Despite your best efforts to do your part in making sure that these practices are done correctly, grub populations can still build to a level that can cause serious damage to your lawn.

Lawn Care Professional ...Your Best Solution
Attempting to control grubs with grub control products available to homeowners can be accomplished if the infestation level is relatively low and the products are applied according to label directions. To achieve results with these products it is imperative that they are properly watered in.

The most effective way to control grubs is to hire a lawn care professional. A lawn care professional will monitor your lawn regularly for the presence of grubs and decide whether or not a treatment is warranted. Lawn care professional's are licensed and have access to a very effective grub control material called Merit®.

Merit is the most effective grub control product registered in Canada. It provides over 90% control of European chafer and Japanese Beetle Grubs. It is normally applied just prior to or during egg hatching of grubs.

Similar to other grub control products Merit must be watered in for it to be effective. The responsibility of watering the product in is normally left up to the homeowner. If the product is applied as a spray it must be watered in as soon as possible, or within 12 hours. If the product is applied as a dry granular through a broadcast spreader it should be watered within a week after treatment or preferably sooner. Both the dry granular and liquid treatments normally require 1/4” of water to properly irrigate them down into the root zone where grubs feed. The product is then absorbed and taken up by the roots of the grass plant. Grubs feed on the roots containing the active ingredient contained in Merit. This essentially causes them to stop feeding, which in turn leads to their control.

If grubs are a concern in your area, ask your lawn care professional about Merit and if the company practices integrated pest management.

Merrit is a registered trademark of Bayer Crop Science.

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