Homeowners with bahiagrass lawns, rejoice: You have one of the easiest grass types to maintain. Not only does it have low water and fertilizer needs, but it also has very few diseases or pests issues. However, no grass is immune from pest problems. We’ve got tips on how to identify, treat, and prevent the three most common bahiagrass pests in your lawn.
In this article:
- Signs you have bahiagrass billbugs
- How to get rid of bahiagrass billbugs
- How to prevent bahiagrass billbugs
Whether you call them bahiagrass billbugs or Sphenophorus coesifrons, these crawling weevils are common enemies of bahiagrass lawns and pastures. Over a few years, bahiagrass billbugs can damage or even kill portions of your lawn.
Bahiagrass billbugs are a type of beetle in the weevil family and range from gray to black. One of the outstanding characteristics of the adults is a long, funny-looking snout that extends from the top of their head. The larvae look similar to white grubs, but in contrast with white grubs, billbug larvae have no legs.
Billbug adults emerge from the soil in late spring and lay eggs in the stems of the grass. Larvae emerge, feed on the stems (and later on the roots), pupate, and emerge as adults in late summer.
Signs you have bahiagrass billbugs
- You see adult billbugs crossing over paved surfaces in late spring
- Hollow grass stems (Eggs hatch inside stems and start to feed.)
- Yellow, tan, or brown grass in irregular shapes
- Patches of dead grass that expand each year or don’t seem to green up in spring. Patches often begin near paved surfaces.
How to get rid of bahiagrass billbugs
The Ohio State University reports that nematodes are often successful for controlling billbug populations. Here are a few strains that have proven successful in small trials:
- Steinernema carpocapsae
- Steinernema glaseri
Follow the manufacturer’s application directions for the best results.
Alabama A&M University recommends two chemical options for controlling bahiagrass billbugs:
- Pyrethroid insecticides
As with most insecticides, timing is important. As soon as you notice adults in your pitfall trap in late spring, it’s time to spray.
How to prevent bahiagrass billbugs
- If you add sod to your lawn, check the roots, crowns, and stems to ensure no larvae or adults have hitched a ride.
- Follow good lawn care practices: Overly managed lawns tend to attract insects and disease. Since bahiagrass is a low-maintenance grass anyway, this may not be an issue, but it’s worth noting.
- Dethatching is not usually necessary, and if you have sandy soils, don’t worry about aeration either.
- Water once per week in heavy soils, or up to three times a week in sandy soils.
- Mow about once per week at 3-4 inches to control seedheads.
- Fertilize with 1-4 pounds of nitrogen per 1,000 square foot. The warmer your climate, the more applications you have time to get in. But remember, over-fertilized lawns tend to attract insects. Go easy and see how the grass responds.
Armyworms are aptly named: In large numbers, they can march across your lawn, leaving a path of destruction in as few as two to three days. They’re not nearly as destructive in smaller numbers, but they’ll still chomp and chew on your lawn. Out of all the armyworm species, in bahiagrass lawns, the fall armyworm is the most likely armyworm species you’ll see.
Fall armyworms are the larval stage of a moth. And yes, in northern states they are most common in the fall or late summer. Adult moths fly long distances from southern locales, mainly Florida, to more northerly locations. For example, fall armyworm moths arrive in New York in August.
In more southern states, such as in parts of Florida, moths don’t travel as far and may be present from April through December and sometimes even further into the winter months. The presence of these adult moths determines how many generations per year an area will have. Adult female moths lay the majority of their eggs within the first five days of their lives.
In northern states, only one generation is common; in the most southern climates, adults are present nearly year-round. Although fall armyworms have been recorded in nearly every state east of the Rockies, these larvae are most economically significant in the Southeast.
Fall armyworms display a wide range of colors, from dark (black, gray, or brown) to lighter colors of green or greenish-yellow. Look for stripes lengthwise on the body and a characteristic upside-down Y-shaped marking on the top of the head.
Signs you have fall armyworms
- Early feeding: Windowpane feeding marks on the grass blades. In their early larval stages, fall armyworms are relatively light feeders, meaning they’ll chew just enough of the grass blade so that a bit of light comes through, hence the term “windowpane.” This is most common on the tips of the grass blades.
- Late feeding: In their last two or three feeding days, they eat 80% of their total larval lifetime’s worth of food. This is why, under heavy infestations, armyworms can demolish a lawn in a matter of a few days. What looked like a drought-stressed patch of grass in the morning may have expanded several feet by the time you get home from work.
- Birds: If you see high numbers of birds congregating in the lawn, check for fall armyworms or other tasty pests.
How to get rid of fall armyworms
Fall armyworms don’t always show up in locust-like levels of destruction. Most years, you may see patches of lawn that start to turn yellow and then brown as the larvae continue to feed. In either case, you probably don’t want them to mar the appearance of your green, lush lawn.
Whether you want a chem-free lawn or don’t mind insecticides, there are options for control:
- Bacillus thuringiensis (Bt)
Note: These products work best on small larvae.
Since fall armyworms may go through as many as five generations per year in the South, you may need to reapply insecticides for year-round control. Plan to treat once you see two or three armyworms in one square foot.
Note: Most off-the-shelf insecticides will get rid of armyworms. Read the label on the back to see the (usually) long list of insects they’ll treat, even if you don’t see armyworms advertised on the front of the bag or container.
How to prevent fall armyworms
- Early control: In an outbreak year, there is nothing you can do to ward off the onslaught unless you happen to catch the armyworms early on. If you notice small spots of discoloration in the lawn, get on your hands and knees to check the grass. “Windowpanes” on the tips are one indication that armyworms may be to blame.
If you can catch a few of the armyworms, send them to your state’s plant-pest diagnostic clinic, or send a pic to your local Cooperative Extension Office for a positive ID. If armyworms are present in the lawn, treat early with low-impact or conventional insecticides to gain control.
- Good lawn care:
- Reduce the insecticides: Insecticides kill good bugs (beneficial insects) as well as bad ones. Use natural control measures (such as a low-impact insecticide) to minimize the effect on these natural predators, including wasps, birds, and wildlife that helps keep armyworm populations in check.
- Bee careful: Low-impact or organic insecticides, including spinosad and some forms of Bt, can be harmful to bees. Often, the toxicity will last a short time, such as until it’s dry, but this is important for homeowners to be aware of. Halofenozide is also less toxic to beneficial animals.
Always read the label — it may tell you whether it is harmful to bees or other beneficial insects.
- Go easy on the fertilizer: Bahiagrass may thrive with as little as 1 pound of nitrogen fertilizer per 1,000 square feet per year (or less if you recycle your grass clippings).
Nitrogen feeds tender top growth, which armyworms love. Try dialing that back a little if you’ve fertilized at a higher rate in the past and had armyworm problems, or take a soil test to know what your lawn needs.
- Water wisely: Proper watering helps create deep roots, allowing grass to withstand stress from insects better. Water two to three times per week if you have sandy soils (common in Florida lawns and along coastlines). For denser soils, water once per week. Aim for 1-1 ½ inches of water total per week.
Mole crickets are to bahiagrass what chinch bugs are to St. Augustine: They are the pest you’re most likely to encounter. Mole crickets inadvertently sever grass roots as they tunnel into your lawn, but they’ll also snack on the grass roots and shoots, causing further damage. You’ll see the most damage to your lawn in spring and fall when adults are most active.
If you’re wondering how a cricket could resemble a mole, here’s how: Mole crickets have claw-like “hands” at the ends of their front legs that allow them to dig and tunnel into the soil, like a mole. The adults range in color from deep brown to light yellow and are around 1 inch long.
Signs you have mole crickets
- Miniature tunnels along the surface of the lawn
- Grass is dying or dead
- Wildlife may dig in the lawn to try to eat the mole crickets
- You spot them at night as they fly, call for mates, or tunnel
- They float to the surface after you perform a drench test on the lawn (The drench test works for many insects, not only mole crickets.)
How to get rid of mole crickets
- Apply nematodes: Beneficial nematodes are microscopic roundworms that help control unwanted pests in the environment. The University of Florida notes that Steinernema scapterisci is one beneficial nematode species that effectively infiltrates mole crickets, releases a bacterium, and eventually kills them.
How to prevent mole crickets
Biological and natural methods
- Wait to water: Mole crickets thrive in moist soil, so let your lawn get a little dry between waterings. Water once the grass shows signs of drought stress (footprints that stay in the lawn, wilting, discolored grass) to save money on your water bill and have a healthier lawn.
- Invite the Larra bicolor wasp into your lawn: Larra bicolor wasps are parasitic insects, meaning they use another insect (mole crickets) as a host for their eggs, killing the host in the process. Install these plants to invite this helpful insect:
- Star flower (Pentas lanceolata) (white)
- Shrubby false buttonweed (Spermacoce verticillata)
- Partridge pea (Chamaecrista fasciculata)
- Use yellow bulbs in outdoor lights or keep them off until several hours after nightfall. Mole crickets are active for 1-2 hours starting at dusk and are attracted to outdoor lighting.
- Pesticides are more common on highly managed turf (such as golf courses) and should be used on home lawns only after you’ve exhausted non-chemical methods. Here are a few chemical options to consider for use on home lawns:
- Bifenthrin (Brand name: Talstar)
- Carbaryl (Brand name: Sevin)
- Clothianidin (Brand name: Arena)
- Fipronil (Brand name: Chipco Choice)
Here’s a short primer on your bahiagrass:
Type of grass: Warm-season grass
Growth habit: Rhizomes (roots that run underground)
Shade tolerance: Not a shade-tolerant grass; needs full sun
Foot traffic tolerance: Low
Drought tolerance: Resistant to drought thanks to an extensive root system, but will go into dormancy during long periods with no water
Diseases: Dollar spot is common
Mowing: 3-4 inches; Get out your mower about once per week during the growing season to remove seed heads
Maintenance: Weed control will be an issue due to open growth habit
Soil pH: 5.5-6.5
Soil conditions: Does well in sandy loam but tolerates most soil types
Other points to note: Grows best in acidic soils. Not saltwater tolerant. Does not produce thick thatch. Requires fewer pesticides than bermudagrass, for example, due to low insect pressure.
Bahiagrass is a low-maintenance lawn primarily found in lawns in the Southeastern United States. It doesn’t just thrive in lawns, though. This versatile grass is also used as a pasture grass, for wildlife habitats, and erosion control.
Look elsewhere if you’re looking for dense sod when you look out the front window. Bahiagrass, like St. Augustine, has a more open growth habit. Bermuda and Zoysiagrass are a better choice if you’re looking for a dense lawn.
If you’d like your bahiagrass lawn to be pest and problem-free, the best way is to hire someone else to maintain it. Contact one of Lawn Love’s lawn care pros to mow, edge, and treat your bahiagrass lawn for any pest problems throughout the growing season.