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Turfgrass Insect Control

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Insects cause millions of dollars worth of damage each year to residential, commercial, and recreational turf. This guide covers the major insects found in South Carolina that cause injury to grasses. It contains important information about the biology of each pest in order to gain a better understanding of how best to control them and when to make pesticide applications. Although it does not cover every insect that causes damage, the ones listed are the most common and problematic.

Not all insects are considered pests in the lawn. Some insects are actually beneficial and prey on damaging insects. It is important to properly identify insects before making a pesticide application. Most lawns will tolerate a certain level of insect damage. Proper cultural practices will greatly increase the lawns ability to recover from damaging insects. Correct irrigation practices and fertility programs are crucial for minimizing pest problems. See your local W.P. Law Inc. store for the latest in irrigation equipment and fertilizer programs. This information is meant to be a guide for insect control in your lawn. Consult all labels for specific information in regards to insecticides and their use. Labels are subject to change and should be adhered to. Always remember, the label is the law.

Grubs are the immature larva of several types of beetles. Grubs will mature through several stages in their life cycle that lasts 1 to 3 years depending on species. In South Carolina, Japanese beetle, masked chafers, and green June beetles all have a one-year life cycle. The only exception to this is the May and June beetles that have a 2-3 year life cycle. Beetles usually lay eggs during the summer months and the adults emerge the following spring or summer once the grubs have matured. Grubs live in the soil and receive their nourishment by feeding on grass roots, thatch, and decaying organic matter. Healthy turf can tolerate 5-7 grubs per square foot of grass.

Mole Crickets

Mole crickets were first introduced into the US in the early 1900’s. Cargo ships from South America brought the first mole crickets into port at Brunswick, Ga. Since then, mole crickets have adapted to southeastern US. Mole crickets prefer sandier soils as they are easier to tunnel through, but can be found in clay soils such as those in the upstate. Each year, mole crickets cause millions of dollars worth of damage to recreation, residential, and commercial sod. Mole crickets can be found in coastal plain soils from Texas to North Carolina.

Chinch Bugs

Chinch bugs feed on various types of grass, but are most problematic on St. Augustine. Adult and nymphs (immature adults) suck sap from the host plant and then inject a toxin that causes it to turn yellow and then eventually die. Symptoms start out small, but can grow as populations reach their peak around mid-summer. Infestations are usually in groups spread throughout the lawn. Multiple life cycles can occur throughout the calendar year with one generation being produced in as little as six weeks.

Adults and nymphs are relatively easy to control, but new populations from eggs may require retreating with an insecticide in 2-3 months. In South Carolina, there are usually 2-3 generations per year. Chinch bugs change significantly in appearance during the five stages of growth. During the first two stages, chinch bugs have an orange appearance with a white band across their abdomen. During the fourth and fifth stages, they appear darker red in color, while finally turning black in color during the fifth and final stage. Adults will have shiny white wings that can be short or long in appearance. Adults will reach a maximum of 6 mm in length.

Chinch bugs feed primarily on the area of the grass between the thatch and the soil. The float method is used to sample for infestations. To test for chinch bugs, take a metal can or cylinder such as a coffee can with both ends open and drive it 2-3 inches into the soil. Fill the can with water. Remove any debris that floats to the surface. Keep the water level at least 2-3 inches deep in the can for a period of 10 minutes. If chinch bugs are present, they will float to the surface. St. Augustine lawns should be monitored on a regular basis. If an area is suspected of having chinch bugs, test the area on the edges of where damage has occurred. In addition to the use of insecticides, there are cultural practices that will help your lawn to resist infection from these tiny organic insects. Avoid over-fertilizing with nitrogen based fertilizers as this can produce succulent tender growth that chinch bugs prefer. Also over irrigating can lead to infestations as chinch bugs prefer moist humid conditions. On St. Augustine lawns, it is important to maintain proper mowing heights of 3-4 inches. Using sharp mower blades can also prevent unnecessary stress to the grass, making it more able to recover from chinch bug damage. Reducing thatch layers also helps reduce chinch bugs infestations, by removing the area they prefer to lay their eggs.

Spittlebugs

There are several types of spittlebugs in South Carolina. The two-lined spittlebug causes the most damage on turf by sucking out sap from the leaf blades with their needle like mouth parts. Centipede grass seems to be the most affected, although these insects will feed on Bermuda, Zoysia, and St. Augustine. Spittlebug eggs over-winter in hollow stems of the grass and in plant debris on the soil. Eggs require high humidity for developing and hatch in May and early June. Two-lined spittlebugs are easily identified by the two orange lines across their backs. There are usually 2-3 generations per year in South Carolina. Young adults (nymphs) are also identified by spittle masses which protect it from drying and natural enemies. These masses look like spit and very indicative of spittlebug infestations. Most healthy stands of grass can tolerate certain levels of infestation. Regular mowing can help to reduce the population of these feeding insects. Mowing before insecticide applications can increase their effectiveness. Damage usually occurs from June through September. Grasses with high thatch and humidity levels favor spittlebug activity. Infestations result in yellowing of grasses.

Fall Armyworms

Fall armyworms are the larvae form of adult moths. Armyworms do not over-winter in South Carolina, so they are generated when moths migrate upward into the state in the month of June. Adult moths can lay up to 1,000 eggs that take from 2-10 days to hatch. Once hatched, small larvae begin to spread in search of food. Fall armyworms prefer lush tender grasses with bermuda being their favorite. Fall armyworms are most active during morning and late afternoon, but continue to feed throughout the day. Fall armyworms feed for 2-3 weeks before they burrow down into the soil and pupate. Within two weeks, adult moths emerge and the life cycle begins all over again. Fall armyworms usually have several generations throughout the year. Armyworms received their name due to their ability to quickly march in and rapidly consume large amounts of turf. Most grasses will recover from fall armyworm damage. Warm-season grasses can be more susceptible to winter kill if damage occurs in late fall. Fall armyworms can damage cool season grasses down to the growing point causing them to die. Fall armyworm pressure may vary from year to year. Cool, wet springs favor the pest due to an absence of natural parasites. Armyworms feed on the above ground tissues of grasses. Areas along wood lines generally are the first to show symptoms of feeding. Fall armyworms are identified by an inverted “Y” mark on the back of their head. Colors of fall armyworms vary from green, to gray, to black. They have a black longitudinal strip down their back and four distinct black dots on the dorsal side of each segment. Controlling fall armyworms with insecticides should begin as soon as minimum threshold levels are met. Generally applications should begin when populations reach one armyworm per square foot. Insecticides work best during the early stage of fall armyworm development. Armyworms can grow quickly over a period of two weeks and insecticide applications will not be as effective on larger armyworms. Repeat applications of insecticides are necessary in some situations.


  Download & Print this Turf Grass Insect Management Instructions by clicking here.