Southern Chinch bugs.
All photos courtesy of Jim Kalisch, University of Nebraska-Lincoln.
The identification and management of surface active insects
By John C. Fech and Jonathan Larson, Ph.D.
Insects that cause damage to turfgrass are generally categorized as surface active (leafzone) or subsurface active (rootzone). If you have to deal with one group or the other, the surface feeders would be the lesser of two evils. Surface active bugs tend to not cause long-term, permanent damage to turf – they don’t feed on the rhizomes, roots or crowns of the plant. Sure, they can make the blades look rough, and even significantly thin the stand, but if the turf is in otherwise good health, more times than not, it will recover. Let’s dig deeper (but not too deep) to see when they pose a greater or lesser threat.
Regardless of the specific habits and life cycle of a surface active insect, or its potential to cause serious harm, management begins with a dedicated, regular, “every week whether you feel like it or not” inspection program.
In most all professions and workplaces, there are workers who go about their various jobs without much thought as to the rest of operation. If you think about your last visit to a big box store, it’s likely that you’ve encountered these sorts of folks – possibly even overhearing utterances such as, “Oh, that’s not my area; I only work in aisles 19 and 20.” In the sports field business, managers and technicians don’t have the luxury to operate this way. Regardless of which aspect of field maintenance they’ve been assigned to, it’s important to have an active role in pest management, even if it’s only an awareness of the most common problems and being on the lookout for current developments.
The key action phrase in this regard is “Look, Look, Look.” This manifests itself in two ways. First, as a bird’s eye perspective when a worker moves from job to job on a given field. They should be looking left and right, as well as straight ahead for signs and symptoms of pests. If copious amounts of ant mounds are spotted or numerous caterpillars are crawling about, this bears further inspection of these “signs.” If brown, burnt or otherwise different-appearing turf is present, these symptoms should be noted, described and documented with further close-up inspections to follow.
Those close-up inspections are the second form of scouting. Using either notes and maps from the previous year/season or seeing obvious symptoms can tell you when to perform such inspections. In this type of scouting – especially considering the possibility of damage from surface active insects – it’s important to look closely at the leaves and at the base of the plants for any sign of a bug.
When scouting, remember to get as up close and personal with the plant as possible. It’s important to keep in mind that it’s not always easy; some critters hide in the thatch, out of view, but are active on the surface. Turf inspections are not done from the UTV or golf cart; it’s an on-your-hands-and-knees activity.
If poking around and looking closely at the leaves and stems doesn’t reveal the presence of any bugs, it doesn’t mean that they’re not there. They just might need a little encouragement to show themselves, which involves a step-by-step process of low mowing, applying a detection mixture and waiting 10 minutes. Two tablespoons of lemon-scented dish soap in 1 gallon of water applied from a watering can over a square yard of turf will irritate likely suspects and cause them to move out of the thatch and come to the surface where they can be observed and identified.
Nationally, the chinch bug group is made up of four possible pests; the common chinch bug, the western chinch bug, the hairy chinch bug and the southern chinch bug. While there are certain key indicators to distinguish one from the other, there are lots of similarities as well. Adults are 1/5 to 1/6 inch long with white and black wings overlapped over their backs. The wings usually cover the tip of the abdomen, with some having shorter or longer wings. They lay eggs over a period of time, with egg hatch varying from 15 to 25 days depending on the temperature and species of chinch bug. Hatching bugs, called nymphs, are tiny and red with a white band across their body, without wings. There are usually five immature stages before the winged adults emerge. Depending on the species and the location of the infestation, there can be between two and 10 generations per year. It is common for the generations to overlap each other.
Chinch bugs damage turf in the adult and nymph stages by injecting salivary fluids into plants as they suck sap from them. It’s common for many bugs to mass together on turf blades and also to hide in the thatch layer of the turf. Their feeding method produces scattered patches of damaged turf that appear to have been sucked dry.
If you have scouted and determined you have a chinch bug problem, there are multiple avenues of control to consider. Chemically, pyrethroid insecticides have often been used curatively against these sucking pests. Bifenthrin, cyfluthrin, deltamethrin, lambda-cyhalothrin, permethrin, and zeta-cypermethrin all are labelled for use against chinch bugs. Neonicotinoid and combination neonicotinoid and pyrethroid products can help prevent damage from occurring if applied according to the label directions.
Culturally, managers can also choose to plant chinch-bug-resistant cultivars or choose species that local chinch bugs don’t prefer. Biological control does naturally occur, with insects like big eyed bugs attaching chinch bugs and fungi like Beauveria bassiana infecting them.
Aphids, also called greenbugs, are commonly seen on turf after having infested grain crops and moved on in search of food once the crops have been harvested. Adults appear as oval to elongated with two small structures called cornicles at the rear end of their abdomen. Aphids are commonly colored black, green, yellow and brown. Adult females give birth to live young during the grain growing season or summer months. As with chinch bugs, generations are often produced and overlap, especially in the southeast.
Aphids use piercing sucking mouthparts to extract cell sap and dehydrate turf plants, rendering them brown and dried out. Looking for the presence of aphids involves inspecting unaffected plants near the edges of their damage.
Greenbugs are often kept in check by natural enemies such as predaceous lady beetles or parasitoid wasps. If a thorough inspection of the leaf blades shows you have a serious enough issue for treatment, you can choose between organic or synthetic products. Products like Botanigard, which contain Beauveria bassiana, or other organics, such as insecticidal soap, can suppress aphid populations. Liquid applications of pyrethroid insecticides such as bifenthrin, cyfluthrin, etc., will also manage greenbugs. Combination products that have these pyrethroids mixed with systemic neonicotinoids can help with aphids and also manage other pests in the turf. Finally, it should be noted that you should not mow or irrigate for at least 24 hours after treatment for these to be effective against these particular surface pests.
The armyworm complex is made up of the true armyworm, the fall armyworm, beet armyworm, and yellow-striped armyworm. 2021 featured a large outbreak of the fall armyworm across much of the United States, so you might be most familiar with it. The adult of the true armyworm is a night-flying moth, colored a nondescript tan to greyish brown, with a tiny white dot in the center of each forewing. The female deposits her eggs in rows or groups on the leaves of grasses and then rolls the blade around them. When fully grown, the larvae are 1-1/2 inches long with two orange stripes on a mostly brown to black body. In the north, two generations per year are common, whereas three are often seen in the south.
The fall armyworm feeds on a variety of agricultural crops, as well as turfgrass. Eggs are laid on grasses in large masses of 100 or more and covered with fuzz from the adult female. Newly hatched larvae are white with black heads, becoming darker as they feed and grow. The fall armyworm is one of the most destructive pests of bermudagrass, with larvae feeding on the lower surfaces of leaves. Larger larvae often eat entire leaves, leaving only the base of the stem. At this point in their maturity, noting the dull black color, several stripes on the body and an inverted “Y” on the front of the head helps to identify fall armyworms. Infested turf takes on a ragged, uneven and sometimes bare appearance as large numbers of worms seemingly move across a section of turf in mere days – hence the name “armyworms.”
As with most caterpillar pests, there are a variety of products that can manage the hungry, hungry members of the armyworm complex. Managers who treat preventively for grubs using chlorantraniliprole will also see that they have prevented damage from caterpillars like armyworms. This is not necessarily true of the neonicotinoids we use for preventing grub problems, so if you rotate to that class for a year be on the lookout for symptoms of caterpillars. Organically, Bt (Bacillus thuringiensis) and Spinosad can control small armyworms if you catch the infestation early enough. If you have already incurred some damage and are looking to stave off more, pyrethroids like bifenthrin, permethrin, and lamda-cyhalothrin can control up to 75 percent or so of larger larvae. Liquid and granular products can work against armyworms due to their proclivity to hide in the thatch layer during the day.
Black, bronze and variegated cutworms are pests of turf, each with descriptions matching their respective names. Black cutworms are dark grey to black in color, without much else in the way of distinctive markings. Bronze cutworms are dark brown to black with three yellow stripes on the upper side of the body and a bit paler on the underside. The variegated cutworm is grey to brown with an orange lateral stripe and a series of darker lateral markings. A row of yellow or white dots run down the middle of the back. Fully grown cutworm larvae of each species reach 1-1/4 to 1-1/2 inch in length, and have a dark-brown to grey head.
As the name implies, cutworms feed on the lower parts of the stem, clipping them off and causing them to fall over and dehydrate.
Management of cutworms is similar to that of armyworms. One physical management method for this group would be to remove clippings from the field and dump them far from those areas. The clippings will contain numerous eggs of these species, and removing them can cut the cutworm problem out before it begins. Aside from that, chlorantraniliprole would again offer extended protection from both grubs and these caterpillars. Systemic clothianidin would also help with both of those issues. To treat cutworms alone, pyrethroids like bifenthrin, deltamethrin, and lambda cyhalothrin would all be options. Organically, Spinosad can help minimize cutworm issues.
Sod webworm larvae are grey to tan with small dark spots on the body and brown heads. When fully grown, they reach 3/4 of an inch to 1 inch in length. They spend the winter as partially grown larvae in the thatch and resume mobility in mid-spring. After a month or so, they emerge as adults, appearing as 3/4-inch tan moths that randomly scatter their eggs into the turf, flying low to the ground in a zig-zag pattern. The eggs take a week to two to hatch and begin feeding on grass stems. In the north, two generations are customary; in the south, the norm is three.
Like cutworms and armyworms, sod webworm moths do not injure turf. Larvae feed in the evening hours, chewing on stems near the soil surface, and then hide in burrows in the thatch in daytime. Small ragged brown spots are the first signs of damage in the turf. Upon close inspection, the stems will have a grazed or scalped appearance. Over time, the spots enlarge and merge together. The most damage occurs in late summer when sports fields are under the greatest stress.
Chlorantraniliprole will provide management of sod webworms. Another biorational option would be Spinosad. As with the aforementioned caterpillar pests, pyrethroid products tend to be a standby control option for spot treatment or outbreaks of these insects. Bifenthrin, cyfluthrin, lambda cyhalothrin and others can suppress sod webworms.
Surface active insect look-alikes
Several causal agents can injure turf and easily be mistaken for surface active insect damage. For this reason, the aforementioned scouting procedures are very important; they help eliminate various insects as responsible influences for the turf decline.
Lawn diseases such as Bipolaris leaf spot, stripe smut, brown patch, anthracnose and summer patch can produce similar symptoms to cutworms, aphids, chinch bugs, armyworms and sod webworms. The key to knowing the difference is to become very familiar with the telltale signs of each, and honing in on them to verify which is responsible.
Severe billbug infestation, which is both a surface and subsurface active insect – causing damage in both above ground stems and throughout the root system – also adds confusion to determining which insect or combination of insects is causing damage to the turf. Hollowed-out stems that break off at the soil surface and shredded roots are typical of billbug damage.
Likewise, heat and/or drought stress will act in concert with the previously mentioned insect species. A small infestation will appear to be much more extensive when the turf is also stressed from inadequate soil moisture or extended periods of high temperature.
Regular scouting, sound fertility and irrigation programs and judicious use of pest control agents all play a part in keeping sports fields healthy and functional.
John C. Fech is a horticulturist with the University of Nebraska-Lincoln and certified arborist with the International Society of Arboriculture. The author of two books and more than 400 popular and trade journal articles, he focuses his time on teaching effective landscape maintenance techniques, water conservation, diagnosing turf and ornamental problems, and encouraging effective bilingual communication in the green industry.
Jonathan Larson, Ph.D., is an Extension professor for the University of Kentucky who provides insect expertise for people dealing with issues in urban landscapes, turfgrasses, nursery crops, greenhouses, and households. He teaches across a variety of platforms using social media, videos, and traditional Extension publications. He is one of the co-hosts of Arthro-Pod, an entomology podcast.
All photos courtesy of Jim Kalisch, University of Nebraska-Lincoln.