Life Cycle - Sometimes adults hibernate in the winter in northern Florida, but all stages are present year-round in most of the state. Eggs are laid in grass sheaths or pushed into soft soil and protected places. In summer, eggs hatch in 10 days and the young develop to adults in 3 weeks. Chinch bugs pass through three generations per year in north Florida and seven to ten in south Florida.
Damage - Chinch bugs are seriously damaging only to St. Augustinegrass but will feed on other grass species. This insect sucks the plant juices through its needle-like beak and also apparently causes other internal injury to the grass, resulting in yellowish to brownish patches in lawns. These injured areas frequently are first noticed along concrete or asphalt paved edges or in water-stressed areas where the grass is growing in full sun. In south Florida, chinch bugs may cause economic damage from March through October; in north Florida, it is usually from April through September.
Monitoring - When chinch bugs are present in sufficient numbers to cause yellow or brown areas in lawns, they can be found by parting the grass runners in the yellowed areas and observing the soil surface and base of the turf where they can be seen moving about. In extremely heavy infestation some of the chinch bugs can be seen crawling over grass blades, sidewalks and outside walls of houses. If no chinch bugs are seen by this method, their presence or absence can be confirmed by using the soap flush described earlier, or by using a metal can such as a three-pound coffee can with both ends cut out. Place one end of the can on the grass in an area where the grass is yellow and declining. Cut the grass runners around the bottom edge of the can with a knife. Twist and push the bottom end of the can an inch or two into the soil and fill the can with water. If chinch bugs are present they will float to the surface within 5 minutes. It may be necessary to add more water to keep the water level above the grass during this 5- minute period. If no chinch bugs are found in the area checked, examine at least three or four other places in the suspected areas. Treatment may be necessary if 20 chinch bugs are found per square foot.
Control
Resistant Varieties - The St. Augustinegrass varieties Floratam, Floralawn,
and Floratine provide various degrees of resistance to chinch bug feeding. Most
chinch bugs cannot complete their development when attempting to feed on Floratam
and Floralawn. Beneficial Insects - Several predatory insects are often
associated with southern chinch bugs. The most prominent predator of chinch
bugs is the black big-eyed bug. A predacious earwig, Labidura, is also
a very good predator on all stages of the chinch bug. An adult earwig has been
observed to eat as many as 50 adult chinch bugs in one night. Big-eyed bugs
and anthocorids (another group of predators) are about the same size as chinch
bugs and are often confused with them. Quite often these beneficial insects
are misidentified as chinch bugs, and a pesticide is applied when it is not
needed.
Control with Pesticides - When it is definitely established that chinch bugs are the problem and the damage threshold has been reached (20-25 chinch bugs per square foot) a pesticide should be applied. Purchase and apply an insecticide that is specifically labeled for chinch bug control. Read and understand all directions on the container label regarding dosage rates, application information and precautions. The treated grass should be irrigated lightly with about 1/8 inch of water to flush the insecticide into the thatch layer where the chinch bugs are feeding. A correctly applied application should provide control of chinch bugs for 8 - 10 weeks.
Several kinds of caterpillars, the immature or larval stage of moths, including sod webworms, armyworms, cutworms and grass loopers may cause damage to all turfgrasses. Bermudagrass is their favorite grass while bahiagrass is the least desirable.
Tropical sod webworms
Description - The most damaging caterpillar is the tropical sod webworm.
The larvae are greenish with many black spots. Adults are dingy brown moths
with a wingspread of about 3/4 inch.
Life Cycle - Eggs are deposited on the grass blades and hatch in about 1 week. Larvae feed on the grass blades and cause noticeable injury within 2 weeks. There may be rather extensive damage within the next 1 to 11/2 weeks until pupation. Adults appear about 1 week later. They complete their life cycle in 5 to 6 weeks and have several generations each year.
Monitoring - Sod webworms are usually not present in sufficient numbers to damage grass before June in south Florida, July in central Florida, and August in north Florida. The webworms feed primarily at night and remain in a curled position on or near the soil surface during the day. This habit makes them difficult to find. Newly hatched caterpillars cause very little visible damage to grass. It is not until they are almost full grown, nearly 3/4 inch long, that their feeding becomes noticeable, and then it appears to show up almost overnight. This, along with their night feeding habit, explains how extensive damage may occur before it is noticed.
The soap flush technique is a good way to detect sod webworms. They may also be found by parting the grass and looking for the small green "worms" curled up on the soil surface and for small green pellets of grass or excrement. A flashlight used at night will reveal the caterpillars feeding in the grass foliage.
Damage - Injured grass has notches chewed along the sides of the blades, which are also eaten back unevenly. The foliage may be almost completely stripped off in patches, and these close-cropped areas soon become yellowish to brownish.
Armyworms, cutworms, and loopers
Description - Armyworms, cutworms, and looper larvae are brown to greenish
in color and have stripes along their sides. Adults of the fall armyworm are
light brown moths with a wingspan of about 1 1/2 inches. When first hatched,
fall armyworm larvae are more grayish-green than webworms and have a stripe
along their sides. When approaching maturity, they are pale brown to black with
large stripes along their sides. On the front of the head is a yellow inverted
"Y" marking.
Life Cycle - Armyworms and loopers may be present during the spring, summer or fall. Armyworms and loopers differ from sod webworms in size and feeding habits. Armyworms, cutworms and loopers grow to about 11/2 inches in length, or about twice the length of the full grown sod webworm.
Damage - Armyworm injury is similar to that of webworms; however, the damage is usually more scattered and not confined to patches as with sod webworm infestations. It is not unusual to have populations of armyworms, webworms, and other lawn caterpillars all feeding at the same time in the same location. Armyworms and loopers feed during the day and do not rest in a curled position while cutworms feed during the night and remain concealed during the day like webworms.
Life Cycle - Mole crickets damage turfgrass in several ways. They tunnel through the soil near the surface and this tunneling action loosens the soil so that the grass is often uprooted and dies due to the drying out of the root system. They also feed on grass roots, causing thinning of the turf, eventually resulting in bare soil.
Mole crickets deposit their eggs in chambers hollowed out in the soil. Most chambers are found in the upper 6 inches of soil but cool temperatures and/or dry soil result in the chambers being constructed at a greater depth. An average female will excavate three to five egg chambers and deposit approximately 35 eggs per chamber.
In north and central Florida, egg laying usually begins in the latter part of March and reaches a peak in May through mid June. Approximately 75% of the eggs are laid during these months. In south Florida, based upon studies in Ft. Lauderdale, egg laying continues throughout the year. Eggs deposited in May and June require about 20 days to hatch; a longer time is required during cooler periods. Peak egg hatching normally occurs during the first half of June in northern Florida and continues through August in southern Florida. A lesser peak of egg hatching occurs in late January to mid-February for the southern mole cricket in south Florida. The young nymphs escape from the egg chamber and burrow to the soil surface to begin feeding on roots, organic material and on other small organisms, including insects.
Damage - Most mole cricket feeding occurs at night after rain showers or irrigation, during warm weather. Some surface feeding has been noted when the soil is dry, but feeding is greatly reduced. All nymphal stages as well as adults come to the surface at night to search for food. Tunneling of more than 20 feet per night has been observed. During the day the mole crickets return to their permanent burrows and may remain there for long periods of time when the weather is unfavorable. Adult mole crickets are strongly attracted to lights during their spring dispersal flights. When mole crickets come to the soil surface, they are subject to predators including fire ants, ground beetles, Labidura earwigs, and Lycosa spiders. Larger animals including raccoons, skunks, red foxes, armadillos, and several toads also feed on mole crickets, but often damage turf areas when searching for them. Research is underway concerning the introduction of several insect and nematode parasites from other countries as biological control agents.
Monitoring - To determine if the mole crickets are present, use the soap flush as described earlier. Check several places in the lawn; if an average of two to three per square foot is detected, a treatment should be applied.
Control - If damage occurred the previous year or if excessive tunneling (egg-laying activity) was noticed in the spring months, a pesticide application will probably be required. Mid to late June is the optimum time for controlling mole crickets in north and central Florida and during late May in south Florida. Use an insecticide specifically labeled for mole cricket control in home lawns. For best results, make sure the soil is moist when the treatment is applied. This aids in the penetration of the spray or granules into the soil, or in the case of baits, encourages the mole crickets to come to the surface to feed on the bait. Immediately following application (except for baits), apply 1/2 inch of water to move the insecticide into the top 1 to 2 inches of the soil.
Ground pearls
Description - Ground pearls are scale insects that live in the soil and
suck the juices from the grass roots. Centipedegrass is the grass most commonly
attacked, but infestations have been found in Bahiagrass, St. Augustinegrass
and Carpetgrass.
Life Cycle - The eggs are laid in the soil during April and May in North Central Florida (Gainesville area). The eggs hatch into tiny crawlers that move about until they locate a feeding site, then they insert their tiny beaks into the grass roots and begin secreting a hard, yellow-brown scaly covering which completely encloses the body. They are round in shape and range in size from a grain of sound to about 1/6 inch in diameter. They look very much like small pearls, hence their name. The adult egg-laying female that emerges from the "pearl" is about 1/6 inch long, pink in color and has well developed forelegs and claws to enable her to move through the soil. Adult males are rarely seen, but resemble a tiny gnat. The life cycle from egg to adult takes at least one year and possibly two years.
Symptoms of Injury - Symptoms attributed to ground pearl injury are first a yellowing of the grass, followed by browning. Ground pearl damage becomes most noticeable when the grass is under stress due to drought, nutritional deficiencies, etc.
Control - All approved practices regarding fertilization, watering and mowing should be carried out to keep the grass growing ahead of the damage. At the present time, it is felt that the benefits gained from an insecticide treatment for ground pearls is not sufficient to warrant an application. This is based on past research and grass response to insecticide treatments.