Identifying and eliminating insects that live at the crown of your lawn

Examples of insects that live at the crown of your lawn are billbug larvae, army worms, cutworms and sod webworms.  These insects live where the grass blades meet the soil.

Billbug larvae we discussed on the insects that live on the grass blades page.  So we will not discuss them any further here.

Army worms

Feeding time is during the day from April until June and then again from August until October.  The larva stage is the most harmful stage.  The larvae live in the soil/thatch and in debris.  Larvae resume feeding in the spring.  They return to the soil to change into adults and lay their eggs.  There can be several generations of army worms in a growing season depending on where you live and the climate.

Army worms are typically 1 inch to 2 inches long.  They are a light tan to a dark brown color with yellow, orange or brownish green stripes down their backs. 

The larvae curl up in the shape of the letter C when you disturb them.  The adult moths are tan or gray with a wingspan of an inch long.  They only fly at night and on overcast days.  All other times you can find them hiding in the soil.

Army worms leave areas with patches of chewed off grass.  They leave tiny fuzz covered eggs on the grass.  Large infestations can demolish your entire lawn.

Army worms tend to like well watered areas.  You may have to evaluate and adjust your watering habits.  Diseases and predators can keep the army worm population from becoming a problem.  If the damage is severe or there are a large number of army worms you may have to use an insecticide to control insects that live at the crown of your lawn.  Make sure to use one that indicates it controls army worms in the lawn.  Mow, rake and water before applying the insecticide.  Spray and granule insecticides work well.  Be sure to always read directions on the package before you use the insecticide.


From insects that live at the crown to the insect damage page

Cutworms

Feeding time is at night or on cloudy days throughout the growing season.  The larva stage is the most harmful.  The larvae sever the plant stems and roots.  In the spring they turn into adults.  When the moths become adults they mate and the females lay eggs in clusters.  When the eggs hatch the worm-like larvae feed and grow.    Several generations grow in one season.

During the larvae stage they reach up to 2 inches long and they are plump.  Most are either black or gray.  Some are spotted or striped.  

As with the army worm, when they are disturbed, they curl up into the shape of the letter C.  The adult moths are brown.  The moths keep a low profile during the day but are active at night.  They are especially attracted to the lights at night.

Cutworms chew the grass stems near the soil surface.  The areas that they feed on wilt and turn brown and spotty.  Cutworms tend to like well watered areas.  You may have to evaluate and adjust your watering habits.  If the damage is severe or there are a large number of cutworms you may have to use an insecticide for insects that live at the crown of your lawn.  Make sure to use one that indicates it controls cutworms in the lawn.  Mow, rake and water before applying the insecticide.  Spray and granule insecticides work well.  Be sure to always read directions on the package before you use the insecticide.

Sod webworms

Feeding time is in the spring through the fall.  The larva stage is the most harmful to your lawn.  The larvae appear and feed in the spring at night or on overcast days.  The caterpillars live in tunnels they make in the thatch or just below the soil surface. As adults they turn into moths.  This usually happens in early summer.  The moths then lay eggs which hatch into larvae within 14 days.  There can be several generations in one growing season.

The larvae are approximately ¾ of an inch long.  They are long and thin grayish caterpillars with black spots.  

The adult moths are a beige color.  You will probably notice the moths before the larvae.  The moths typically fly out of the lawn as you are mowing.

Sod webworms like the hottest and driest areas of your lawn.  They cut off the grass blades below the soil or thatch line.  The grass appears to be thin in areas. Dead patches tend to be 1-2 inches wide.

If there is a lot of damage you may have to treat your lawn with an insecticide for insects that live at the crown of your lawn.  Make sure you mow and rake before you apply the insecticide.  Read the package label to make sure the product controls sod webworms in the lawn.  As always read the directions before you apply the insecticide.

If there is a lot of damage you may have to treat your lawn with an insecticide for insects that live at the crown of your lawn.  Make sure you mow and rake before you apply the insecticide.  Read the package label to make sure the product controls sod webworms in the lawn.  As always read the directions before you apply the insecticide.

As with weeds and lawn diseases, your best defense in controlling insects that live at the crown of your lawn is a healthy well maintained lawn.  Be sure you mow, water and fertilize your lawn appropriately.  Also, make sure that your grass is thick and there are not any sparse areas that need to be filled in.


Army worms


Cutworms


Sod webworms

Damage caused by Sod Webworm