Lawn & Turf Tips:  Bluegrass Billbugs

Bluegrass Billbugs

Although not as common, bluegrass billbugs can be responsible for severe trufgrass damage. They seem to cluster in neighborhoods, especially where intensive bluegrass management is occurring. Adult bluegrass billbugs are weevils, or snout beetles, with mouthparts located at the end of a curved snout or bill. Although bluegrass billbugs rarely fly, they may rapidly spread through continuous lawns of a neighborhood.

Life Cycle

Billbugs have a one year life cycle. They winter over as adults in sheltered locations in and around turf grass areas.

• The Adults are active in late April and May, when soil temperatures are above 65 degrees.
• They lay their eggs at the crown of bluegrass stems.
• When hatched, the larvae begin feeding on those stems which, in some cases, kills the plant.
• As the larvae grow, the leave the stems and move into the soil feeding on the roots of the plant
• Once they have completed their feeding around mid-July, the larvae pupate in the soil or the thatch.
• In late July, the Adults emerge from the soil and move to the overwintering sites.

Symptoms or Signs of Damage

• The adult billbugs feed on the stems and blads of the grass but do not cause much damage.
• The young, newly hatched larvae feeds on the inside of the grass blade or stems. They hollow out the crown and stem of the plant and leave behind fine sawdust like plant debris and excriment.
• As the larvae grow and get larger, they feed on the roots of the plant as deep as 2"-3" below the surface of the soil. This is when they do the most damage to the plants. When the number of larvae is large, root systems can be almost completely destroyed killing the grass.
• The damage caused by the billbug larvae is often mistaken for grub damage, sod webworm damage, disease, heat or drought stressed turf.
• The greatest damage from billbug larvae is during late June to Late August.
• Where the grass has been killed by the larvae, it comes loose from the soil and separates easily.
  

Control

Before you consider a treatment for billbugs, it is strongly advised that you first make sure that they are the cause of your turf damage. The larvae are difficult to find before they move down into the soil. This occurs in late June or July. By that time, significant damage may have already occurred. The adults can be difficult to detect as well. You can find them during the months of mid-April and May. The easiest way to find them is to flush them out by applying the turf area with 1 tablespoon of 1-2% pyrethrins in one gallon of water over a one square foot surface area. If you wait 15 minutes, they will come to the surface.

Cultural Control : The different bluegrass varieties are susceptible to the billbug and sustain the worst of the damage. Most perenial rygrasses, particularly those with endophytes, are more resistant to to them. If you plan on reseeding or overseeding and are in an area that has been heavily infested, it is highly recommended that you use a grass seed blend that has the more resistant grass varieties in it.

Chemical Control for Adult Billbugs: This tends to be the most common means of control. Insecticides, either contact or stomach poisons, are applied when the adults come out of their hibernation and are migrating to where they will lay their eggs.

Chemical Control for Summer Larvae: An insecticide application can also be applied in the summer once the larvae have dropped out of the stems.

If you suspect that there may be a problem with your lawn, please call us so we can come out and identify what is going on.