• Topics: Entomology and Nematology  | Athletic Fields  | Non-residential Lawns  | Turfgrass (IMG -- Vol. 1, Ch. VI)  | Lawn Insect Pests  |  Turf & Sod Pests: Insects & Mites  | Turfgrass Pest Insects  | Turfgrass Pests  | Buss, Eileen A  | Turner, Jaycee L 

Insect Pest Management on Turfgrass¹

Turfgrass is grown in many environments and for different uses, such as home lawns, parks, athletic fields, cemeteries, rights-of-way, golf courses, sod farms, and pastures. The intensity of turfgrass management largely depends on the particular species or variety of grass and its intended use.

Several insects and mites feed on grass, but not all of them cause economic or aesthetic damage. Many are harmless, some are beneficial, and some are pests. Only a few cause significant damage and need immediate control. Keep in mind that insects are only one of many potential causes for thin or brown grass. Diseases, nematodes, drought, and nutritional disorders can also be damaging. Correct identification of the problem can save money and prevent unnecessary pesticide applications.

The biology and management of the most important pests of turfgrasses in Florida are described in this publication. Pesticides labeled for insect control in turfgrass are listed in Table 1. Information regarding formulations is described in Table 2. In general, healthy turf is less vulnerable to pests and can recover faster from an infestation. Avoid overusing soluble nitrogen fertilizers, mow at the correct height for the grass species, reduce thatch, and avoid over-watering. Check every 7 to 10 days for pest activity, especially in "hot spots" where damage tends to reoccur.

Armyworms

The fall armyworm, Spodoptera frugiperda (Figure 1), is the most common armyworm species in Florida. Caterpillars first skeletonize the grass blades and later create bare spots.

Figure 1. 

Fall armyworm.

The caterpillar is greenish when small, dark brown when mature, and can reach up to 1½ inches in length. It has a light midstripe on its back with darker bands on either side. The midstripe ends in an inverted "Y" on the head. Pupation occurs in the soil. Adult moths are brown with a wing span up to 1½ inches. Eggs are laid on leaf blades or almost any object near lawns.

In coastal areas of north Florida, moths mainly occur from April to December. Summer generations may develop in 30 days, 60 days in spring and autumn, and 80 to 90 days in winter. Mature larvae feed continuously during the day and night.

Monitor by mixing 1 TBSP of liquid dishwashing soap in 1 gallon of water; pour the solution onto 4 square feet near the damage. Insects will crawl to the surface if present. Examine several suspected areas. Adults fly to lights at night.

Bermudagrass Mite

The bermudagrass mite, Eriophyes cynodoniensis (Figure 2), is tiny (about 1/125 inch long), and just visible with a 15- to 20-power hand lens. It is creamy white in color, somewhat wormlike in shape, and has 2 pairs of legs.

Figure 2. 

Bermudagrass mite.

Bermudagrass is the only host for this mite species. The cultivars FloraTex, Midiron and Tifdwarf are resistant, but Tifway and other varieties are susceptible to the mite. The leaf tips of infested grass yellow slightly and internodes and leaves are shortened. This results in a tufted look or "witches' broom" effect. Large areas of grass may die and become infested with weeds. Damage is worse during hot, dry weather.

One generation develops in 5 to 10 days. All life stages (eggs, nymphs, adults) live under the leaf sheath. Mites may disperse on the wind, other insects, or grass clippings. Infestations usually develop in the taller grass (rough areas, around sand traps, along canals, fence rows, etc.), so keep grass mowed as low as possible.

Cutworms

Several species of cutworms (e.g., black or granulate cutworms) (Figure 3) occur in Florida, but seldom are serious pests in turfgrass.

Figure 3. 

Granulate cutworm.

Larvae usually dig a burrow in the ground or thatch (or use an aeration hole) and emerge at night to chew off grass blades and shoots. Damage may appear as circular spots of dead grass or depressed spots that look like ball marks on golf greens.

Larvae are mostly hairless, have 3 pairs of true legs and 5 pairs of fleshy prolegs on the abdomen. (Most cutworms curl up when disturbed.) Moths are generally dull-colored with wing spans up to 1½ inches. Eggs are laid randomly on leaf blades, and hatch within 10 days. Three to seven generations may occur each year.

Monitor using a soap flush, as described for armyworms.

Fire Ants

The red imported fire ant, Solenopsis invicta (Figure 4), is an introduced pest that creates large mounds in turfgrass and inflicts painful bites and stings to people, pets, livestock, and wildlife. Mounds can also damage mowing, harvesting, or electrical equipment.

Figure 4. 

Red imported fire ant.

Red imported fire ants are aggressive, reddish-brown ants that are 1/8 to 1/4 inches long. Mounds (up to 3 feet wide and 1 1/2 feet high) often occur in sunny, open areas. If a mound is disturbed, many ants immediately emerge to defend their colony and attack intruders. For more information, see Imported Fire Ants on Lawns and Turf (ENY-226).

They are social insects and live in colonies. White immature ants ("brood") include eggs, larvae, and pupae. Adult ants have different jobs ("castes"), including winged males, winged females, workers of varying sizes, and one or more mated queens. New offspring are produced in the spring.

Ground Pearls

Ground pearls, Margarodes spp. (Figure 5), are scale insects that attack the roots of bermudagrass, St. Augustinegrass, and zoysiagrass, but prefer centipedegrass. They occur in Florida's panhandle, south to Pinellas and Polk Counties.

Figure 5. 

Ground pearls.

Ground pearls suck juices from plant roots, which makes irregular patches of grass look unhealthy. Grass yellows, browns, and dies, especially in hot, dry weather. Weeds tend to invade infested areas.

Clusters of pinkish-white eggs, covered in a white waxy sac, are laid in the soil from March to June. Tiny crawlers attach to roots and cover themselves with a hard, yellowish to purple, globular shell. These "pearls" range in size from a grain of sand to about 1/16 inch. They may occur as deep as 10 inches in the soil. The adult female is 1/16 inch long, pink in color, with well developed forelegs and claws. Adult males are rare, tiny, gnat-like insects. One generation may last from 1 to 2 years.

No management strategies, including insecticides, are currently available for ground pearls. Minimize plant stress and maintain proper fertility and soil moisture to help grass tolerate the damage.

Hunting Billbug

Hunting billbug, Sphenophorus venatus verstitus (Figure 6), larvae are white, legless grubs with brown head capsules. Adults are black beetles (weevils) with chewing mouthparts at the end of the "bill." Adults have a raised Y-shaped area surrounded by curved lines on the prothorax and rows of large and small pits on the wing covers.

Figure 6. 

Hunting billbug adult and larva.

Hunting billbugs have two generations per year, but all life stages may be present at a time. Eggs are laid in the leaf sheaths or top of the crown and hatch within 10 days. Young larvae feed on the inner leaves and chew down to the roots. Pupation occurs in the soil or roots and may last up to 7 days.

Zoysiagrass, bermudagrass and seashore paspalum are preferred hosts. Most damage may occur in the fall, when populations are high. Damage may be misdiagnosed as dormancy in the fall, and dead patches or areas that green up slowly may be noticed in the spring. Stems and rhizomes break easily and have many irregular feeding marks. Infested sod will not hold together when cut. Most damage occurs on infertile or dry soil.

Monitor off-color areas by cutting 1 square foot of sod, 2 inches deep. Lay back the sod and examine roots for chewing damage and check soil for larvae. Adult activity may be monitored using soap flushes. Parasitic nematodes (Steinernema and Heterorhabditis) and Beauveria fungi may effectively control billbug larvae and adults.

Mole Crickets

Three exotic mole cricket species (tawny, southern, and short-winged; Scapteriscus spp.) are significant pests in Florida. The native northern mole cricket is rarely a pest.

Damage is caused by mole cricket tunneling in the soil, which exposes and dries out roots. Nymphs and adults of the tawny (Figure 7) and short-winged mole crickets are vegetarians, and feed on roots and grass blades at night. Bermudagrass, bahiagrass, and centipedegrass are often attacked. The southern mole cricket is mainly a predator, feeding on small soil animals, but, it also eats plant material.

Figure 7. 

Tawny mole cricket.

Adults grow to be 1½ inches long. The front legs are flattened and adapted for digging. The tawny and short-winged mole crickets are golden brown with a mottled brown pronotum (located on the back between head and abdomen). The tawny mole cricket has a V-shaped space between the two dactyls (digging claws). The short-winged mole cricket has short wings and cannot fly. The southern mole cricket is grayish brown, has 4 pale-colored dots on the pronotum, and a U-shaped space between the two dactyls.

Monitor using a soap flush. Southern and tawny mole cricket adults are attracted to light, especially in the spring. Nematodes, especially Steinernema scapterisci (Nematacs®), are effective at reducing mole cricket populations.

Scales/Mealybugs

The most common pest in this group is the Rhodesgrass mealybug, Antonina graminis (Figure 8). It prefers Rhodesgrass, Johnsongrass, bermudagrass, and St. Augustinegrass.

Figure 8. 

Rhodesgrass mealybugs.

Infested grass plants gradually turn brown and die. St. Augustinegrass may become discolored and develop spots. An appearance of fertilizer caked around the grass nodes indicates a heavy infestation..

Females will deposit 300-600 eggs in a cottony ovisac without mating (no males exist). The crawlers disperse and begin feeding under a leaf sheath at a node. A white waxy sac, roughly spherical, is secreted around them. After settling, the insects will not move again.

Cultural control includes collecting and destroying grass clippings.

Southern Chinch Bug

Southern chinch bugs, Blissus insularis (Figure 9), suck the juices from St. Augustinegrass at or just below the soil level. Injured plants look stunted, yellowed, wilted, or dead. Yellowish to brownish patches are often first noticed along sidewalks or in poorly-irrigated areas.

Figure 9. 

Southern chinch bug.

Chinch bug adults are about 1/5 inch long, black with white patches on wings, which are folded over the back. Young nymphs are reddish-orange with a white band across the back. Body color darkens and becomes black as nymphs reach adult size.

Activity is reduced in winter in northern Florida, but all stages are present year-round in most of the state. Eggs are laid in leaf sheaths or crevices and cracks in nodes and other protected places.

To monitor, first part the yellowing or declining grass to look for moving insects on plants and in thatch. Insert a metal can with both ends cut out near damaged turf. Fill the can with water and wait 5 minutes for chinch bugs to float to the top. Examine at least 3 or 4 places.

Cultural controls include reducing the amount of water soluble nitrogen fertilizer used. Mow at the recommended height for St. Augustinegrass. Read St. Augustinegrass for Florida Lawns (ENH-5) for more information. Minimize thatch buildup. Monitor and spot treat the damaged area and a 5 foot area surrounding it, if necessary. None of the commercial St. Augustine varieties are completely resistant to chinch bugs.

Spittlebugs

The two-lined spittlebug, Propsapia bicincta (Figure 10), is the most common leafhopper-like insect to damage turfgrasses, especially bermuda, St. Augustine, centipede, bahia, crab, Johnson, and orchard grasses. It also feeds on many crops, ornamentals, and weeds.

Figure 10. 

Two-lined spittlebug.

Nymphs and adults both suck plant juices through their straw-like mouthparts. In centipedegrass a reddish-purple and/or white stripe may run lengthwise down damaged grass blades. Heavy infestations may kill, wither, or reduce the growth of turfgrasses.

Nymphs may be yellow, orange, or white, and are covered by a frothy mass of spittle. Adults are about ¼ to ½ inch long, black with two reddish-orange lines across the wings. Eyes are dark red.

About 2 generations occur each year. Eggs are laid in hollow stems, beneath leaf sheaths, or in thatch. Eggs overwinter and nymphs emerge in the spring to feed in humid, protected areas. One generation may last about 2 months.

Tropical Sod Webworm

Tropical sod webworm, Herpetogramma phaeopteralis, larvae (Figure 11) are gray-green, and have brown spots on each segment. Mature larvae can be about ¾ to 1 inch in length. Larvae remain curled up in the soil during the day and feed at night. Newly hatched larvae skeletonize the grass blades, while older larvae chew on grass blades near the soil surface.

Figure 11. 

Tropical sod webworm.

Damage begins in small patches of short-clipped grass, about 1 to 3 inches in diameter. The grass may look ragged, and irregularly-shaped, larger brown patches may form. Small, green frass can be seen on the ground.

Sod webworm adults are small, tan to gray moths with a wingspan of ¾ to 1 inch. They do not cause damage. Moths hide in shrubs and other sheltered areas during the day, begin flying at dusk, and lay eggs randomly on grass at night. Eggs hatch about a week later.

This pest is most active from April through November, but may occur year-round in southern Florida. Three generations occur in northern Florida and four generations in southern Florida. Use a soap flush to monitor for damaging populations. For more information, see Biology and Management of Tropical Sod Webworms (ENY-318).

White Grubs

Several white grub genera occur in Florida, but the most damaging are Cyclocephala, Cotinus, Phyllophaga, and Tomarus.

Larvae are fat-looking grubs which lie in C-shaped positions (Figure 12). They are whitish in color with dark areas at the rear and a brownish head. The adults are scarab beetles.

Figure 12. 

White grub.

Round, white eggs are laid singly in moist soil. Grubs live in the soil and feed on grass and other plant roots. Most species other than Phyllophaga beetles complete 1 generation a year in Florida. Grubs become most damaging in August and may continue feeding until January. Many adults are present from April to June. Adult masked chafers fly again from August-September. The adults do not feed on grass, but some may be pests of ornamental plants or fruits.

Too much organic matter in the soil, using organic fertilizers or over-irrigation during adult flights may increase susceptibility to infestation.

To monitor, watch for adult scarab beetles flying at night near lights. To monitor white grub populations, cut 2-3 inches deep in a 1 foot square area of damaged grass. Lay the grass back, check the quality of the roots, and look for grubs in the soil.

Additional Information

For more information, please refer to these UF extension publications:

• Ants (ENY-203)

• Chiggers (ENY-212)

• Fleas (ENY-205)

• (ENY-221)

• Ticks (ENY-206)

• Formulations Comparison Chart (ENY-418)

• Insecticide Application Concerns (ENY-417)

• Insecticide Safety (ENY-416)

• Insecticides Used in the Urban Environment: Mode of Action (ENY-282)

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.

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