The symptoms of insect damage to turf are often more obvious than the type of insect causing the damage. The following key will help you identify the pest species by close examination of the damaged area. Remember that many insects and even some diseases and fertility problems cause injuries that may look similar. Identifying the pest based on symptoms alone is often impossible.
Use this key to aid in identifying insect problems and to determine which detection technique to use. In general, if insects are causing the problem, they should not be difficult to find. After narrowing the problem to an insect or group of insects, use the appropriate detection technique to find the insect.
To use a key, begin searching at couplet number 1 for the appropriate damage description. The selection will give either the name of the insect pest or another couplet number. If it gives the name, you have the pest; if it gives a number, continue the process until you find the appropriate insect pest. For example, for soil mounds or holes in the soil, couplet one refers you to couplet three, which lists possible pests. Several Cooperative Extension Service publications provide photographs and line drawings of the insects to aid in identification. They include publication AG-268, Insect and Other Pests Associated with Turf, and AG-348, Turfgrass Pest Management Manual.
Every 7 to 10 days during the growing season, inspect the turf for pests. In the case of insect damage, inspect immediately using the proper technique. Correctly identify the problem before applying a treatment.
Chinch bugs. Insert a large metal can with both ends cut out (other similar material will work) into the turf in an area where the grass is yellowed and declining. Fill the can with water. Wait 5 minutes for the chinch bugs to float to the top of the water. Examine three or four places in the suspected area. Parting the grass to observe the soil surface for chinch bugs also works. Treat if you find an average of 20 or more chinch bugs per square foot.
Sod webworms, mole crickets, armyworms, and other caterpillars. Mark off a 1-square-yard area in a location of suspected infestation. Mix 2 fluid ounces of liquid dishwashing soap in 4 gallons of water and drench the area with the solution. Insects will emerge to the grass surface. Kneel to observe the area closely. Insects will return to the soil in 5 or 10 minutes. If no insects are found, examine other suspected areas. Treat if you find in the 1-square- yard area an average of 40 or more sod webworms; three or more mole crickets; or eight or more caterpillars.
White grubs. Cut three sides of a 1-square-foot piece of sod about 3 inches deep with a spade at the edge of one of the off-color areas in the turf. Pull or pry the sod black like a flap and examine roots for chewed off remnants and check the soil for grubs. Use your fingers to sift through soil and roots. Treat if you find three or four grubs per square foot.
Other Insects. Closely examine turf for evidence of damage by other insect pests (ants, bees, wasps, and leafhoppers). Always check the turf where the damaged area meets the green, healthy grass. That is where the insects are likely to be most abundant.
* Degree of importance as pest: I = Important pest, frequent occurrence; II = Usually present, but generally not a pest; III = Occasional pest, treat when detected.
** Preferred grass species: A = Centipedegrass, fescue, and many other grasses; B = Saint Augustinegrass; C = Fescue; D = Bluegrass; E = Bermudagrass; F = Zoysiagrass; G = Bentgrass; H = Bahiagrass.