Regional Insect Control
Do you sometimes feel as though you'll never rid turf of insect pests? You conquer one only to find that another has taken its place? It's no wonder. There are more kinds of insects on the earth than any other kind of living creature. In fact, 95 percent of all the animal species on the earth are insects. And millions can exist on a single acre of land — hopefully not an acre of land that you manage. And while many of these insects have common characteristics, usually, national appeal isn't one of them. For the most part (and with the exception of the crane fly [leatherjacket], which was targeted by two regions this year as Enemy No. 1), region is going to dictate which insects give your turf the most problems, as different regions are more conducive to different insect environments.
As such, we have asked university experts in five regions of the United States to identify what they perceive to be their area's most troublesome insect pest (defined either by the damage they can cause to turf, sheer number or, in some cases, the fact that they are often misdiagnosed) and methods you can use to control them.
If, after reading, you are disappointed to not find your most irritating insect pest described here, please don't be. This article is designed to expose only those insect pests with the dubious honor of being bad enough to capture the attention of the researchers we invited to contribute. Even though the information is representative on a national level, it is not intended to be comprehensive. However, as these experts are in touch with the pests that worry turf managers most, they probably have a good idea of the ones that have been bugging you. Here's what they had to say.
By Daniel C. Peck, assistant professor
Cornell, Geneva, N.Y.
In 2004 leatherjackets (the larvae of crane flies) were detected for the first time in extreme northwest New York. This includes two species: Tipula paludosa (T.p., the European crane fly) and Tipula oleracea (T.o., the Marsh crane fly). By the end of 2005, we confirmed populations all along the Erie Canal corridor from Buffalo/Niagara to northeast of Syracuse.
Both species can be problematic in any grass-based system, from low- and high-maintenance turf, like home lawns and golf courses, to production-based systems like sod farms and grass seed fields. All turfgrass species appear to be susceptible. Populations are favored by mild winters and wet, cool summers, and in areas with moist soil conditions and thatch buildup.
Larvae cause injury in two ways. In the soil, they feed on root hairs and roots, pruning and disrupting the rooting zone like white grubs. When larger, they will also graze on the surface like black cutworms. Western New York in 2005 was witness to populations as high as 40 per square foot in irrigated home lawns and scalping damage in the form of “ball-marks” on putting greens.
There are many species of native crane flies in the Northeast, and a few occur in grassy habitats. None, however, has ever been linked to damage. The injurious invasive species can be recognized in several ways. First, adults will emerge from over a 2- to 3-week period approximately in May (T.o.) and September (T.o. and T.p.). They can be abundant and noticeable as they flit about low in the turf, often congregating during the day on the sides of buildings, sliding doors, window screens and fences. Adults are about an inch long and look like gigantic mosquitoes. In low-mown turf (greens, tees), it is easy to spot the pupal exuvia the adult leaves behind when it emerges. These pupal cases, or “leatherjackets,” look like small black twigs sticking up from the ground.
If signs of insect activity and turfgrass injury suggest leatherjackets, core sampling is the best way to detect and sample larvae. Inspect soil cores for the larvae by digging up from the soil to find them in the rooting zone, and also inspect down from through the grass into the thatch to find those that may be on the surface. On low-mown turf, disclosing solutions (based on dilute detergents or insecticides) may force some larvae to the surface so you can capture them. When mature, larvae will be almost an inch long. Eggs are not detectable in the field; they are black, about 1 mm long, and are laid at the soil surface. The habitats most likely to harbor leatherjackets are lower-lying protected areas, irrigated lawns and other areas with continual moisture.
T.o. completes two generations a year and is thought to have a greater dispersal potential due to the behavior of the adults. T.p. only completes one generation a year but is probably the more problematic of the two species because it is expected to rapidly build up populations in areas where it has established. Once eggs hatch, larvae grow rapidly, usually achieving third instar before cold temperatures force them to descend in the soil profile. When conditions warm again in the spring, they emerge to continue feeding and development. Injury will be most likely expressed in May when they are as large as they will get. By early June, larvae have stopped feeding and descend once again in the soil profile where they will aestivate in an inactive non-feeding state until pupation in late August. Depending on health of the sward, action thresholds range from 15 to 50 larvae per square foot. Vertebrate predators may contribute to substantial predation over the winter season, so just because thresholds are surpassed in the late fall does not mean that populations have not declined considerably by early spring.
Cultural controls include draining chronically wet areas. Any other careful manipulation of soil moisture and irrigation is also expected to suppress populations given the susceptibility of eggs and small larvae to dry conditions. Avoid irrigation in the late fall. There are two windows for applying control products against larvae. In the late fall, preventive applications can target eggs and small larvae, but sampling to assess thresholds is impossible to do at that stage. The other option is an early spring treatment that can be applied as warranted given damage or sampling. If both species are present, the fall application will be target both; in the spring, however, T.o. is inactive or in pupation so it will not be affected by control products.
By Eileen Buss, assistant professor
University of Florida, Gainesville, Fla.
The biggest insect problem on golf courses and sports turf in the Southeast may be a toss-up between fire ants and mole crickets. In residential turf, it may be chinch bugs or spittlebugs. But, billbugs, which are small browish-black weevils (less than ½ inch long), may frequently be present as well, and their damage is often misdiagnosed.
Billbug damage often resembles drought injury, other insect or disease damage, or delayed spring green-up. Infested turfgrass thins, patches of turf die, stems break easily and adults make tiny push-up mounds. Infested stolons will look dead, are broken about ½ inch from the crown and have frass inside. You may even be able to see a small exit hole. Damage is most obvious when turf has low fertility and low soil moisture.
The hunting billbug (Sphenophorus venatus vestitus) is considered the most damaging billbug species in transition and southern turf areas, but it occurs north to New Jersey and west to Texas. Its primary hosts are bermudagrass and zoysiagrass, but it also attacks bahiagrass, centipedegrass, St. Augustinegrass, orchardgrass, crabgrass, signal grass, barnyardgrass, corn, sugarcane and leatherleaf fern.
The hunting billbug is actually part of a billbug complex in southern turfgrass. Although 25 species occur in Florida, only seven infest turf (S. apicalis, S. cariosis, S. coesifrons, S. inaequalis, S. minimus, S. parvulus and S. venatus). Their life cycles have not been thoroughly studied. Hunting billbug is thought to have at least two to three generations each year, with the greatest abundance of adults from November to December and again in April to May, but adults are found every month of the year. Billbug adults deposit one to two eggs into small holes that they chew into grass crowns and stolons. Each female may lay more than 200 eggs. Tiny, legless larvae feed inside the stems, then move into the soil and feed on turfgrass roots. Larvae pupate in a soil chamber about 1 to 2 inches deep.
Some options that are available for controlling billbug infestations include host plant resistance, biopesticides and preventive or curative insecticides. Several resistant cultivars of bermudagrass and zoysiagrass (Zoysia matrella cultivars Diamond, DALZ9601, Cavalier and Royal) exist. Perennial ryegrasses with endophyte fungal enhancements are considered resistant to billbug attack, and could be used as overseed in the fall. Applying insect-parasitic nematodes (e.g., Steinernema carpocapsae, Heterorhabditis bacteriophora) may help reduce billbug populations. Any specific parasitic wasps or predators of billbugs are currently unknown.
Chemical control of billbugs can be difficult. Preventive control of billbug larvae using typical preventive grub insecticides (e.g., halofenozide [Mach 2], imidacloprid [Merit]) has variable efficacy, depending on your location. Generally, they are applied when adults are laying eggs, so the residuals control the young larvae. Most turfgrass managers in Florida have been aiming their applications (e.g., acephate [Orthene or Precise], bifenthrin [Talstar]) against adults.
Knowing when adults or larvae are present is crucial. Monitor for billbugs using a shovel or cupcutter and sift the top 3 to 4 inches of soil near damaged areas to look for adults or larvae. If billbugs are an ongoing problem, try placing small cups or pitfall traps in the soil and periodically check them for adults that have fallen in. In general, if you find more than 10 to 15 billbugs per square foot, a treatment is warranted.
By Thomas E. Eickhoff, Ph.D. student; Tiffany M. Heng-Moss, assistant professor; and Frederick P. Baxendale, Extension entomologist University of Nebraska, Lincoln, Neb.
Over the past 15 years, the western chinch bug, Blissus occiduus, has emerged as a serious insect pest of warm-season turfgrasses in Nebraska and other mid-western states. The western chinch bug was first detected in Nebraska infesting a heavily damaged buffalograss lawn in the early 1990s. Since its initial discovery, it has been found associated with buffalograss throughout Nebraska and surrounding states. This chinch bug has now been detected in zoysiagrass and, since the summer of 2000, the University of Nebraska has received numerous inquiries from homeowners about this chinch bugs in their zoysiagrass lawns.
The western chinch bug overwinters as an adult and has two generations per year in Nebraska. In both buffalograss and zoysiagrass, damage first appears as reddish-purple discoloration of the leaves followed by patchy areas that turn yellow and dry to a straw-brown color as feeding progresses. At higher infestation levels, chinch bug feeding can result in severe thinning or death of the turfgrass stand. You can detect chinch bugs by removing a small section of turf and vigorously shaking it over a sheet of white paper to dislodge the insects. An alternative method for detecting chinch bugs involves attaching a mesh bag to the end of a leaf vacuum and vacuuming a small area of turf with a suspected chinch bug infestation. Examine the contents of the bag for the presence of chinch bugs. If chinch bugs are estimated to exceed 20 to 25 per square foot of turf and feeding damage is present, control is most likely warranted.
The use of sound cultural practices and maintaining a high-quality turfgrass stand will help the turf to tolerate low chinch bug infestations. Because these insects prefer turf areas high in thatch and organic debris, mowing and cultural practices that minimize thatch accumulation will discourage initial infestations and may even help reduce existing chinch bug problems. A second approach for deterring chinch bug infestations involves planting chinch bug-resistant turfgrasses. Research at the University of Nebraska has shown that the seeded buffalograss cultivar Cody and the vegetatively propagated cultivar Prestege are highly to moderately resistant to western chinch bug feeding. Likewise, the zoysiagrasses Cavalier, El Toro, Emerald, Palisades and Zoro also have moderate levels of resistance to this chinch bug. It is important to remember, however, that heavy chinch bug infestations can damage even these resistant turfgrasses.
Insecticide efficacy trials conducted at the University of Nebraska indicate that applications of insecticides containing the active ingredients bifenthrin (Talstar) or carbaryl (Sevin), provide effective chinch bug control. In order to improve the efficacy of your insecticide treatment, mow the turf to a height of 1.5 to 2 inches and remove the clippings prior to the application. This will minimize interception of the insecticide by the turf canopy. Immediately following application of liquid formulations, irrigate the treated area with ⅛ inch of water to wash the insecticide off grass blades and down into plant crowns and thatch where chinch bugs are feeding. If you apply a granular insecticide, irrigate the turf with at least ¼ inch of water to activate the insecticide. In areas where chinch bug numbers are very high, you may need to make two insecticide applications to achieve satisfactory control. You should apply the first treatment when chinch bugs are still small (typically in late May to mid-June), and the second in late July.
Western chinch bugs can be effectively controlled though sound turfgrass management practices, use of resistant turfgrass cultivars and/or the use of insecticides. However, as with any turfgrass pest, routine scouting and early detection are critical in quickly identifying and remedying the pest problem.
By Tom Cook, associate professor of horticulture
Oregon State University (Corvallis, Ore.)
Compared to the rest of the United States, the Pacific Northwest has only modest insect pressure. It is entirely possible to maintain turf for a lifetime here without having to treat lawns with an insecticide. Given that insects are not normally a major problem in lawn care, we do have one insect that is with us every year.
European crane fly, Tipula paludosa, has been in the Pacific Northwest since the mid 1960s and has steadily moved south through western Washington and western Oregon with potential to move along the coast to at least the San Francisco Bay area in California. Recently, there have been reported infestations in central Oregon and there has been at least one report from the Spokane area in eastern Washington. A second crane fly, Tipula oleracea, has also been observed in association with European crane fly but has never been shown to cause turf damage.
European crane fly produces one generation per year, with adults hatching from August through October. Mating occurs just after adult emergence, followed by egg-laying and hatch of first instar larvae from mid September through October. Larvae develop into the third instar stage by early December. The third instar is the stage that does most of the damage via feeding on both roots and shoots. Peak activity often occurs in February and March, which coincides with damage symptoms. Early symptoms often involve turf thinning. Thinning to 50-percent cover can be tolerated in most years without long-term lawn damage. Unfortunately, more severe infestations can virtually eliminate turf cover.
Because many other problems can mimic damage from crane flies, it is important to determine larval populations before deciding to treat with insecticides. Monitoring, in areas west of the Cascade Mountains, starts in January on sites with a history of crane fly activity and February on sites with no history. To conduct larval sampling, cut a 6-inch square of turf about 3 inches deep. Break up the soil and count the larvae and multiply by 4 to calculate the number of larvae per square foot. Twenty five to 50 larvae per square foot and visual signs of thinning indicate that you need to treat with an insecticide to prevent turf loss. If you don't observe thinning, continue to monitor every two weeks through April. If no damage is observed by then, no further action is needed. Carbaryl (Sevin) and bifenthrin (Talstar PL) are registered for control of all larval stages. Imidacloprid (Merit) is effective when applied at the first instar stage in early fall, although this amounts to preventive spraying, which is rarely advisable.
Experience has shown that drought stress during the egg-laying and first instar stages often reduces larval populations dramatically and minimizes the chance of damage the following spring. In general, stopping irrigation just after Labor Day is effective in most years. In western parts of Washington and Oregon, previously irrigated lawns will generally remain green without irrigation after Labor Day until the onset of fall rains.
Turf managers should monitor extensively for crane fly this year starting immediately. The mild and very wet winter we are experiencing has been perfect for crane fly larval development.
By Kai Umeda, turfgrass science area Extension agent; and Gabriel Towers, research specialist University of Arizona Cooperative Extension, Phoenix, Ariz.
A network of blacklight traps set up in and around the Phoenix and Scottsdale area on golf courses during 2004 and 2005 determined a key pest of turf in the desert. Masked chafer beetles were the predominant species that were trapped during the summer months from May to October. Other night-flying insects observed in the light traps included moths of sod webworm, armyworms and cutworms. Other beetles from the white grub complex that were observed included June beetles, black turfgrass ataenius (BTA) and Aphodius species. During 2004, data collected at six sites demonstrated that the beetles began to appear in mid- to late-May with flights peaking in early June and in July, followed by a third peak flight in September. The peak number of beetles collected was variable among all of the locations, with some sites consistently having less than five beetles per night and others showing more than 20 beetles per night in the light traps. In 2005, eight sites were monitored and similar beetle flight patterns were observed with high numbers of beetles trapped during June to July and then again during September. The peak number of beetles was not distinguishable between June and July 2005, but the high number of beetles trapped was consistent during the period from late May to mid July, followed by another peak flight in September. The occurrence of two distinctive peaks for masked chafer beetles may be accounted for by the emergence of two different species of masked chafers in the Arizona desert. Similar beetle flight patterns were observed previously during the mid-1990s in the southern California desert by Pace Turf Research Institute.
The insect pest trapping survey determined that masked chafers are the predominant species with occurrences of BTA and non-pest Aphodius beetles. The insect pest trapping technique offers turf managers site-specific data by identifying potential pests and when they occur. Knowing when peak flights of masked chafers occur, you can accurately time an application of an insecticide if necessary. In Central Arizona, we have not fully determined economic threshold levels to initiate treating for grubs. Many times, the appearance of birds feeding on turf or javelinas rutting on greens indicate when to trigger insecticide applications. The monitoring of blacklight traps will indicate when a peak flight of masked chafer beetles occurs and enable calculating when an appropriate insecticide might be applied.
The occurrence of two distinctive peaks in flight of masked chafers complicates how a you would approach treating for potentially turf-damaging grubs. A single application of a soil-applied residual insecticide at about three weeks after the first peak flight would not continue to provide control of the population occurring in the fall. Typically, the neonicotinoid insecticides such as imidacloprid (Merit) or newly introduced clothianidin (Arena) should offer effective control of the smaller instar grubs. An imidacloprid + bifenthrin combination product (Allectus) was recently introduced and efficacy is still being evaluated. Halofenozide (Mach 2) and trichlorfon (Dylox) are also commonly applied for grub control in the desert. The efficacy of a half-rate of a split application of a soil-applied residual insecticide has not been fully determined for the desert. It is not known if a second insecticide application in the fall would be effective when it is during the overseeding period in the desert. The adoption of trapping techniques and monitoring insect pest populations will enhance integrated pest management (IPM) strategies for turf management. Further field research is also being conducted to determine effective and precise control strategies.
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