Insect Control

Grub Control

Step 1. Determine the extent of your grub infestation:

Not all lawns have grub infestations that warrant control. Lawns differ in susceptibility to white grubs because of differences in grass species, soil health, irrigation, amount of sun or shade, traffic, etc. A dense stand of grass with a healthy root system can generally tolerate up to 10 grubs per square foot, although skunks, raccoons, birds and moles sometimes damage turf, seeking grubs in lower densities.

To determine how many grubs you have in your lawn you can use a flat spade to cut back a sample of turf. Count the grubs in the top 3 inches of soil and replace and water the turf. If you take a 6" X 6" sample (1/4 of a square foot), a grub density of more than 2-3 per sample probably warrants treatment. Take a dozen or so samples throughout the lawn area to determine which areas may need treatment.

Step 2. Grub Identification:

There are several white grub species, Japanese beetles and Oriental beetles are the most common species, but we find quite a few Asiatic garden beetles and European chafers as well. It is best to get your grubs identified to the species level to optimize choice of insecticide against these pests.

Step 3. Treat in the Fall:

It is tempting to treat white grubs in the spring when damage is apparent, but spring treatments are generally ineffective. The large grubs present in the spring have already done most of their feeding and caused their damage and are now difficult to kill with insecticides. It is better to overseed damaged areas in the spring and wait until late summer to sample for a new generation (concentrate sampling in previously-damaged areas - they tend to return to the same area of your lawn).


Chinch Bugs

The chinch bug is a common lawn pest that sucks sap from grass with its piercing mouthpiece. Chinch bug damage gives the appearance of small round dead patches (brownish-yellow grass) and opens up areas for weeds to become established. When not controlled, large sections of lawn may die. This is particularly true of sunny, dry areas near slopes and the edge of lawns. Chinch bugs also cause damage when they feed and inject a toxic saliva into the grass causing it to wilt and die. Population size depends on the weather, with only small populations being produced under wet conditions. However, if the weather is hot and dry early in the season with minimal amounts of rainfall, a large population may occur.

Adult chinch bugs are black with shiny white wing covers Chinch bugs are found feeding on the soil surface and on tips of grass.



It is easy to confuse improper lawn care with chinch bug damage. Therefore, it is important to monitor your lawn to determine if damage is caused by chinch bugs or lack of moisture and/or over-fertilizing. Begin monitoring for chinch bugs in June before populations reach high numbers. There are several effective monitoring methods to try if you suspect chinch bugs are attacking your lawn. One option is to take a large can, cut both ends off and push it down into the top layer of the lawn. Pick an area of the lawn where brown-yellow or dead patches of grass meet green healthy grass, as this is where chinch bugs can be found. Fill the can with water and watch for chinch bugs to float to the top.

Another option involves first drenching the damaged area with soapy water. Then place white flannel sheets over the area and within 15 to 20 minutes chinch bugs will be attaching themselves to the sheet to escape the soap. Finally, when large numbers of chinch bugs are present, they are found in sections of the lawn where the healthy grass meets the damaged sections.


A well fertilized and nutrient-rich area can withstand a chinch bug attack. Thus, good lawn care is the best prevention against chinch bug damage. Understanding chinch bugs, the conditions they favour and their life cycle is very helpful in control. Keep the lawn well fertilized and take caution not to add too much or too little nitrogen. Use proper mowing techniques which include cutting grass two to four inches (6-7 1/2 cm) high, removing thatch, maintaining proper moisture levels, avoiding water buildup, aerating the lawn if it is compacted and using a resistant variety of grass.

If you are establishing a new lawn or reseeding an old one, use a resistant variety of grass which will offer protection against attack by chinch bugs. An example of a resistant variety is an endophytic grass which contains a fungus that repels attack by chinch bugs and other insects.


If physical methods are not effective, use a pesticide which will have a minimal impact on both you and the environment. Use an insecticidal soap spray on areas where damage has occurred. Diatomaceous earth can also be used to control chinch bugs. Diatomaceous earth is an insecticidal dust which acts as an abrasive. It cuts the outer layer of the chinch bug's body causing it to dehydrate and then die. Products containing pyrethrin can also be used.

Sod Webworms

There are several species of caterpillars called sod webworms that can be highly destructive pests to your lawn. They may also become important pests of grass covered parks, cemeteries, golf courses. Damage to grass is caused by the feeding of the larval or "worm" stage. The adult moth does not cause damage to turf, other plants or clothing.

The damage caused by sod webworms may first appear in early spring. The damage shows up as small dead patches of grass among the normally growing grass. The summer generation may cause general turf thinning or even irregular dead patches in late June into early August. Sod webworms prefer sunny areas and the larvae are often found on south facing, steep slopes and banks, where it is hot and dry. Heavily shaded turf is seldom attacked by the larvae.

The most severe damage usually shows up in July and August when the temperature is hot and the grass is not growing vigorously. In fact, most sod webworm damage is mistaken for heat and drought stress. Sod webworm-damaged lawns may recover slowly, without irrigation and light fertilizations.

Recognizing Sod Webworm Injury

The general thinning of turf is usually not associated with sod webworm activity, and thus, goes undiagnosed. The sod webworm caterpillars live in tunnels constructed in turf thatch or extending to the soil under the turf. These tunnels are silk lined and the webbing joins soil particles and leaves together. The larvae emerge from these burrows to chew grass blades off just above the thatch line, usually at night.

In thick, green turf, injury appears as small brown patches about the size of a quarter to three inches in diameter. When many larvae are present in mid- summer, the small brown patches run together and form large irregular, thin and brown areas.

Confirming Sod Webworm Activity

The surest way to tell if you have sod webworms is to find a suspected area of infestation (brown patches). Get down on your hands and knees, take your two index fingers and part the grass blades in the area between dead and live grass and look for an area with small green pellets. The pellets, called frass, are the excrement of the larvae and indicate that a larva is close by. Sod webworm adults are about 3/4-inch long, cigar-shaped and buff-colored moths. They typically roll their wings around the body when resting on a grass blade.

If you still suspect sod webworm activity but are unable to find the larvae or their frass, use a soap disclosing drench. Simply mix up two gallons of tap water with two tablespoons of liquid dishwashing detergent. Sprinkle this mix over a one square yard of the affected turf. Within a couple of minutes, the flesh-colored, spotted larvae will wriggle to the surface. If you get 10 to 15 larvae in a one square yard of turf, treatment is warranted.

Control Hints

Control should only be directed towards the feeding larvae, not the flying adults. Since drought stress and turf diseases can cause thinning similar to sod webworm damage, be sure to check the turf for frass or use the soap disclosing flush to determine that larvae are present.

Strategy 1: Cultural Control - Use Fertilizer and Water - Damage can often be outgrown if water is continually available. Considerable damage may occur if irrigation is not possible during periods of drought or close mowing is used.

Strategy 2: Use Resistant Turfgrass Varieties - Turfgrasses with fungal endophytes are generally resistant to sod webworm attacks. Look for perennial ryegrasses, tall fescues and fine fescues that have "Endophyte Enhanced" on their package. The seed of these grasses can be overseeded or slit seeded into existing lawns.

Strategy 3: Chemical Control - Use Contact and/or Stomach Pesticides - Most webworms are easily controlled if the pesticides are ingested when the larvae feed shortly after dark. Therefore, best control is achieved by spraying in the late afternoon. Late fall or early spring applications are often not effective because many larvae are hiding in deeper soil chambers.