Key to Turf Insect Damage
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.
Detecting and Monitoring Insect Pests
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.
|Couplet No.||Description||Refer To...|
|1||Soil mounds or holes in soil||Couplet 3|
|Above symptoms not apparent||Couplet 2|
|2||Defoliation; grass blades chewed off or stems severed at or above soil line||Couplet 4|
|Turf discoloration more apparent symptom, grass yellow or brown and dried out||Couplet 5|
|3||Burrow opening associated with a mound of soil||Ants, wild bees, cicada killer wasps, or green June beetles|
|Burrow opening without corresponding mound; mostly found during summer months||Sod webworms|
|4||Plants severed near ground line||Cutworms or sod webworms|
|Plants not severed near ground line; leaves skeletonized, completely devoured, or eaten around the edges||Fall armyworm or armyworm|
|5||Grass yellow and dried out; white frothy "spittle" apparent||Spittlebugs|
|No white, frothy "spittle" mass||Couplet 6|
|6||Yellow spots in grass (St. Augustine grass only) that soon become brown and die; small black and white bugs (1/5 inch long) are noticed on soil surface||Chinch bugs|
|Not as above||Couplet 7|
|7||Various-shaped yellow and brown patches in lawn; puncture holes in grass stems and crowns and circular holes in leaves||Billbugs|
|Not as above||Couplet 8|
|8||Small white spots on shoots of browning turf||Leafhoppers|
|No white spots, few or no insects above ground||Couplet 9|
|9||Irregularly discolored areas of turf that may be closely cropped||Cutworms or sod webworms|
|Not as above||Couplet 10|
|10||Grass yellowed (primarily centipede, but other grasses also), pearl-like insects in soil below damaged areas||Ground pearls|
|Grass appears to be dying of drought; moderately easy to pull yellowed grass from soil||Couplet 11|
|11||Tufts of discolored grass easily pulled up; puncture-like holes in stems and crowns; circular holes in leaves||Billbug grubs and adults|
|No holes like above||Couplet 12|
|12||Some grass plants uprooted (primarily bahiagrass, but other grasses also); small slightly raised tunnels along soil surface||Mole crickets|
|No tunnels||Couplet 13|
|13||Large, irregular brown patches of turf; if infestation is severe, dead turf can be rolled back like a carpet; c-shaped grubs in soil||Grubs|
|Irregular yellow or brown patches of turf, small dirt mounds resembling ant hills; c-shaped grubs in soil||Green June beetle grubs|
|Pests||I*||P**||When to Scout for Insects and Mites|
|Armyworms and cutworms||III||A||S|
|Bees and wasps||II||A||S|
|Green June beetles||I||A||S||S|
|Leafhoppers and spittlebugs||II||A||S|
|* 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.
S = Sprays; Gr = Granules; Ba = Baits; M = Maintain the turf in healthy condition, irrigate
Publication date: April 1, 1998
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