Lawn Insects of Colorado

Common Insects That Attack Grass

There are numerous insects that can attack a lawn, but ninety nine percent of these pests can be prevented and cured without using any insecticide or chemicals. The key to preventing or curing a lawn disease is to have proper lawn care cultural practices.

The key to preventing insects from attacking a lawn is to create an environment that is suitable for the grass, but is hostile to the insects. The best way to do this is to allow the soil to completely dry out between lawn watering. The 1-2-3-2-1 lawn watering technique is the ideal way to water a lawn if you want to prevent insect pressure from attacking grass.

Preventing Insect Pressure in Lawns

Sound Cultural Practices are The Key to a Healthy Lawn!

The key to treating and preventing lawn insects is as simple as creating an environment which is not hospitable to insects. When the environment in the lawn is in balance and the lawn will look great! There might be a few insects but there won't be enough to cause harm to a lawn.

That being said all species of plants are subject to insect pressure. Due to improper lawn watering practices, white grubs have become a larger problem in lawns in the last few years. Grubs cause the majority of insect problems in grass. These problematic grass feeding insects can become extremely destructive and can spread quickly if the environmental conditions are ideal for them to lay eggs.

The most effective grass insect control in Colorado is to maintain proper lawn care cultural practices, such as proper lawn mowing techniques, the use of organic lawn fertilizers, proper lawn watering (deep and infrequent watering), core aeration, and avoiding the use of lawn chemicals.

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Insects that Attack Lawns in Colorado

Billbugs in Lawns

Billbugs are a type of weevil or “snout beetle.” Adult weevils are typically seen on driveways and pavement from late spring through late summer. Adults can cause minor injuries to lawns because the females cut small holes in the stems of plants and as they lay their eggs.

Billbug grubs are the main cause damage to lawns. Billbug grubs are white or cream colored, with a brown head. They can reach 1/3 to 1/2 inch long when fully grown. Young billbug grubs feed within the crown area of the grass and can kill the turf. It is easy to tell if a lawn has been attacked by grubs because the grass will pull up from the ground like a freshly laid piece of sod. Older billbug larvae feed in the lower crown and plant root zone. Small piles of sawdust-like material are produced during this stage of feeding.

Billbug injury is most common in lawns with shallow root structures. Within lawns, most damage occurs near evergreen shrubbery like juniper bushes, spruce or pine trees. Billbug injury appears as wilting and occasional death of grass, often in small scattered patches. Extensive areas of a lawn may be killed during severe infestations.

Preventing billbug injury to grass is easy. Lawns with deep digging roots will be able to tolerate insect pressure from billbugs. Following the principals of the 1-2-3-2-1 lawn watering technique will promote deep digging grass roots in a lawn. Annual core aeration and using only high quality organic fertilizers will also stimulate deep digging grass roots. Insecticides are only necessary in the most severe cases of billbug pressure in a lawn.

Chinch Bugs

Chinch bugs are quite uncommon in Colorado. Spot infestations have been reported in some Denver area lawns but they are not a common lawn problem in the Boulder or Fort Collins area. The chinch bug species recorded from turfgrass sites in Colorado is the hairy chinch bug,

Chinch bugs can cause damage to lawns because they feed on grasses. Several species of chinch bugs are known to cause damage to turfgrass in parts of the United States. Feeding injuries cause wilting and occasionally plant death. Chinch bug outbreaks are associated with hot, dry weather and proper irrigation suppresses these insects.

Since the chinch bug is not a major insect that causes problems in Colorado we do not recommend treating for this insect. Following the 1-2-3-2-1 lawn watering technique will be very beneficial in controlling chinch bug outbreaks if they do occur.

Cranberry Girdler

Cranberry girdler grubs can be found throughout the U.S. and it can be particularly damaging to lawns. Larvae prefer cool-season grasses, such as Kentucky bluegrass, bentgrass and fine-leaf fescues. In addition to causing significant damage to turfgrass, it is recorded as a pest to cranberry plants, Douglas fir trees, and true fir trees. Cranberry girdlers move from infested grasslands to trees.

Although cranberry girdler eggs and pupae can be easily confused with other sod webworms found in turfgrass, the larvae and adults are distinctive . Heavy infestations can kill turfgrass when the larvae feed on the roots of the grass. Damage symptoms look similar to white grubs feeding damage where the sod becomes loosely attached to the soil. The first evidence of turfgrass injury begins as small brown patches in late summer when larvae are near maturity. Widespread infestations can quickly accelerate damage and create large dead areas of sod by early fall.

The easiest way to prevent the cranberry girdler is to water the lawn according to the 1-2-3-2-1 lawn watering technique. The reason this works is because the adults lay their eggs in lawns during the month of July. They will only lay their eggs in lawns that have wet soils. If a lawn is being watered according to the 1-2-3-2-1 lawn watering principals the soil will completely dry out between lawn watering, and the adults will not be able to lay their eggs in the lawn.

If it is too late to water the lawn properly to avoid infestation and an problem does occur. We recommend an application of a special insecticide called Acelepryn.

Dry Lawn or Drought Stress

Drought stress is not an insect but it is the leading culprit for brown lawns in Colorado. Improperly adjusted sprinkler heads that miss areas of the lawn when watering is one of the biggest lawn care problems of Colorado. About 90% of brown spots in lawns are caused by either poor sprinkler coverage or improper lawn watering techniques.

During the hot summer months of June, July and August and during prolonged periods of drought are when we see the worst brown spots appearing in lawns. Many homeowners assume that a brown spot in the lawn is a disease or insect problem, but the majority of the time the brown spots are caused by sprinkler heads that are not adjusted properly, are blocked by plants, or are not functioning properly.

It is easy to recover a brown spot that is caused by poor sprinkler head coverage. Start by adjusting or fixing the sprinkler head coverage issue and then water the brown spot for 3 consecutive days. Follow up by making sure that the lawn is being watered according to the 1-2-3-2-1 lawn watering technique. If the area cannot be watered properly by making adjustments to the sprinkler heads, hand watering with a hose and sprinkler head will fix the dry spot.

Leafhoppers in Grass

Leafhoppers are a common insects in lawns. These very small insects are typically less than 1/6-inch large. Their color is variable but many of the more common turfgrass species are generally light colored or light brown.

The adults are normally only noticed when one walks across a lawn or mows the grass. These activities disturb the insects, causing them to fly or jump off the blades of grass.

Leafhoppers suck the sap from the blades of grass. Rarely are there any visible effects from leafhopper feeding on the leaves, and damage is insignificant. At most, feeding may result in small whitish spots on the leaf.

Controlling leafhoppers is hard to justify. Leafhoppers cause very little damage to a lawn, but they do attract attention and some find them to be a nuisance. The use of insecticides to control leafhoppers can not be justified in regards to concern about the health of the lawn. The best way to prevent major infestations of leafhoppers is to water the lawn according to the 1-2-3-2-1 lawn watering technique.

Mites - a.k.a. Lawn Mites, Banks Grass Mites, Clover Mites or Spider Mites

Grass mites can be very problematic to lawns during hot and dry winter months. These very small insects are almost impossible to see with the naked eye. Mites can be a variety of different colors, but during dry periods, particularly when mites are found indoors, they are a often a brick-red color. Grass mites feed on grass roots and blades with their rasping-sucking mouth parts and in a bad infestation they can desiccate the grass often to the point of death.

Lawn mites are usually found on the south facing sides of buildings, rock beds, sun exposed slopes and pine trees. The mites often feed on the grass from November to March during warm and dry weather and take shelter in pine trees and buildings during cold and wet weather.

Controlling lawn mites is easy. Grass mites hate water and a great way to prevent spider mite damage is to water the lawn during prolonged periods of drought stress, especially during the winter months. The water that is applied to the lawn will discourage the mites from feeding on the lawn and it will supply the grass with additional moisture to prevent desiccation. Lawns that have been watered according to the 1-2-3-2-1 lawn watering principals will have deep digging grass roots and therefore will be less likely to be be killed by grass mite pressure.

If watering the lawn is not an option grass mites can easily be controlled with an organic insecticide called Ecotrol. Lawn mites are a very common problem in Colorado during extended warm period in the winter months. We have a dedicated web page with more information about lawn mites and the best ways to control them.

Sod Webworm

Sod webworms one of the most common lawn insects found in Colorado lawns. The adult moths do not feed on the lawn, but female moths lay eggs which hatch into small caterpillars.

Sod webworm larvae are about 1/4 to 1 inch long caterpillars, brown or gray in color, and they have rows of dark spots on their backs. During the day, young webworms live in silk-lined tunnels in lawns that have thatch or at the surface of the soil. At night they emerge from their tunnels to feed on the leaves of the grass.

Even though sod webworms are commonly found in lawns, if the grass is healthy and strong the damage they cause will not affect the appearance of the lawn. Properly cared for lawns that receive regular organic fertilizer applications and lawns that are watered according to the 1-2-3-2-1 lawn watering technique will be healthy enough to withstand substantial webworm populations. Birds feeding on the larvae will often prevent the webworms from causing visible damage to the turf.

White Grubs - Japanese Beetle Grubs

Due to irrigation, White grubs are becoming more common a major problem for lawns in Colorado. White grubs feed on grass roots, which result in large brown spots in the turf. The damaged turf can be easily peeled up from the soil surface as if it was a freshly laid piece of sod.

Most lawns have a few white grubs in them, but suffer no visible damage. When population are high, however, large areas of turf can be killed. The presence of grubs (even when turf damage is minimal) can also be revealed by foraging raccoons and skunks – which will dig up large sections of lawns overnight in search of this favored food.

Controlling white grubs can be accomplished by allowing the soil to dry out during the month of July. Grubs will only lay their eggs in soil that is moist or wet. Lawns that are being watered according to the 1-2-3-2-1 lawn watering technique rarely are attacked by grubs, because the soil dries out between lawn watering.

By the time damage become noticeable, grubs are often so large and it is more difficult to kill them with insecticides. When grub activity is occurring an application of a special insecticide called Acelapryn is very effective in controlling grubs. We have a dedicated web page with more information about grubs and the best ways to control them.

How to Kill Grubs in a Lawn

What Is The Most Effective Way to Prevent Lawn Insects?

Rotary Sprinkler Head

1-2-3-2-1 Lawn Watering Technique

Maybe you didn't notice that every lawn insect in Colorado is preventable by watering according to the 1-2-3-2-1 lawn watering technique.

Most lawn insects prefer lawns that are compromised via improper cultural practices like poor irrigation management or mowing the lawn too short. If the lawn is suffering from insect pressure, we will draw up a plan to first stop the cause with the lawn problem and then fix the insect problem. Our permanent fix will usually involve making simple but important changes: such as adjusting mowing height and adjusting watering schedules. We only use insecticides as a last resort because they usually completely unnecessary.

Before applying any insecticide to your lawn, call our offices today to schedule one of our professional lawn care technicians to come out to perform a disease diagnosis. We do charge for this lawn care service, but we waive all or some of the fee if you end up using our recommendations to correct the lawn care problem. Remember the first step in repairing a grass problem is properly diagnosing what is causing the issue to occur in the first place.


Organo-Lawn is your local lawn care expert and can explain in Layman's terms what is causing the lawn to have brown spots. Call today to talk to one of our professional lawn care technicians. (303) 499-2000 Boulder or (970) 225-9425 Fort Collins


FAQ - Lawn Disease and Lawn Fungus Identification

Which insects causes the most damage to Colorado lawns?

There are two insects that do the most damage to lawns in Colorado. The Banks Grass Mite causes the most harm to lawns during the winter months in Colorado. Lawn mites suck moisture from grass during extended warm and dry periods during the winter months. They tend to do the most damage to lawns that are south facing and have shallow digging grass roots.

White grubs from the Japanese beetle do the most damage to lawn in Colorado during the months of September and October. White grubs feed on grass roots, which can result in large dead or brown spots in the turf. The damaged turf can be easily peeled up from the soil surface as if it was a newly installed piece of sod.

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How to prevent lawn insects without using chemicals?

Following the 1-2-3-2-1 lawn watering recommendations is one of the most important steps to preventing insect pressure in lawns. Improper lawn watering practices are the main cause of 99% of lawn insect pressures. The most effective defense to infestations is to maintain proper lawn care cultural practices, such as proper lawn mowing techniques, the use of organic lawn fertilizers instead of chemical lawn fertilizers, proper lawn watering (deep and infrequent watering), core aeration, and avoiding the use of chemicals.