Billbugs 101 - Symptoms, Scouting and Treatment

Billbugs are serious pests of lawns and other turf areas.  The four most common species are the bluegrass, hunting, Rocky Mountain and the Phoenician billbugs. Typically, billbugs only cycle through one generation each year in the northern climate and two (or more) generations in the South.  In most climates, billbug adults overwinter in thatch, soil crevices, under mulch or leaf litter and return in mid-to-late spring as the soil surface temperatures rise above 65°F. However, there are indications that some species may overwinter as larvae.
 
Billbug Characteristics

Adult and larval billbug. David Shetlar, The Ohio State University, Bugwood.org

Billbug Larvae:
  • Curved, cream-colored bodies without legs, brown heads
  • Eggs in turf stems hatch in three to ten days, depending on the temperature
  • Young larvae feed inside the grass stem
  • After the 1st and 2nd instar stages, they may break out of the grass stem and feed on grass crowns, roots and stems
 Adult Billbug: 
  • 0.3 to 0.4 inches in length and black, dark gray or brownish in color
  • Pronounced, curved snout where the chewing mouthparts are located
  • Lay oblong, creamy white eggs inside grass stems near the base of turf plants
  • Feed on grass stems and blades, but cause only minor injury to the turf
Geographic distribution of billbug species
Hunting billbugs are widely distributed, appearing from New Jersey to Florida, through the Gulf into Texas, and north to Kansas and Missouri. The hunting billbug feeds on zoysiagrass, bermudagrass, bahiagrass, St. Augustine grass, centipede grasses and cool-season turf species.
 
Bluegrass billbugs are found in the northern states from New England to Washington in:
  • Kentucky bluegrass
  • Perennial ryegrass
  • Fescue
Phoenician and Rocky Mountain billbugs are found in the western states from intermountain regions of Utah and Colorado to the California coast. It is common to find them among hunting or bluegrass billbugs.
 
Symptoms
Damage from billbugs frequently appears from late March through early August.  In fact, the spotty, yellow/brown patches of turf can be mistaken for white grub damage, drought stress, disease or even late spring green-up in warm-season turf species.  Left untreated, heavy infestations can lead to extensive browning and even turf death. 
 
Scouting
Newly-hatched billbug larvae tunnel within grass stems, hollowing out the stem and leaving light brown frass (excrement) near the crown of the plant. The presence of frass is a good indicator of a billbug infestation.  You can also try pulling the stems of affected grass. If the stems break off at or near the crown of the plant, this will indicate presence of billbugs.  Also, small larvae may be found near the crown of the plant and upper zoot zone.

Billbug damage on a home lawn. David Shetlar, The Ohio State University, Bugwood.org

Pitfall traps are effective for monitoring adult billbug activity. Take a small plastic cup to dig out a few areas of the potentially infected turf. Next, place the cup with the lip even to the soil surface. If placed properly, the pests will fall into the cup when they move around on the turf.1   Another way to identify billbug adults is to scout cart paths, sidewalks and driveways on warm sunny days. 
 
Treatment
Adult billbugs are difficult turfgrass insects to control because the bodies of the adults do not readily absorb insecticides and first instars of billbug larvae feed inside grass stems.
 
Systemic insecticides are recommended to control larvae since they chew on the stems, crown and roots of grass. Products such as Meridian® and Acelepryn® insecticides will provide broad-spectrum control against billbugs and all white grub species. Meridian should be applied approximately six weeks after the adults become active (pitfall trap monitors) to target the larvae inside the stem and in the soil. Acelepryn should be applied earlier, or about two weeks after adults become active. Acelepryn will also control the billbug larvae. Make sure to water-in the application to move the active ingredient into the soil profile where it can be most effective.
 
In areas where both zoysia patch and hunting billbugs are present, you can treat these two problems with one cost-effective application of Caravan™ G insecticide/fungicide. Caravan contains the insecticide active ingredient, thiamethoxam and the fungicide active ingredient, azoxystrobin.
 
1  Miller, L. (2012, July 2). Hunting billbugs – emerging problem for zoysiagrass in Missouri. Retrieved from Division of Plant Sciences - University Of Missouri Integrated Pest Management website: http://ipm.missouri.edu/meg/2012/7/Hunting-Billbugs-Emerging-Problem-for-Zoysiagrass-in-Missouri/
 
©2015 Syngenta. Important: Always read and follow label instructions.  All products may not be registered for sale or use in all states. Please check with your state or local Extension Service before buying or using Syngenta products. Acelepryn®, Caravan™ and Meridian® are trademarks of a Syngenta Group Company. 

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