Billbug

Facts, Identification & Control

Scientific Name

Sphenophorus spp.

Appearance

Adult billbugs are beetles in the weevil family. Depending on the particular species, they are about ½ to 1 inch long, gray to brown in color and possess a snout that some compare to a miniature version of an elephant’s trunk. The insect’s larval stage is grub-like in appearance, white and with no legs.

Billbug
Billbug image licensed under CC

Behavior, Diet & Habits

While billbugs can be serious pests of corn and grasses important to agriculture, the most likely problem encountered by the homeowner is damage to garden crops and lawn grasses. In most cases, billbugs spawn one generation a year, but reproductive capabilities can vary depending on species and location. Unless homeowners carefully inspect their lawns or hire a pest management professional, it is not uncommon to first notice adult billbugs moving across driveways, patios and sidewalks. If you see this, call your pest management professional and get their help to identify the insect. Adults usually overwinter in leaf litter and lawn thatch prior to laying eggs in a chamber they cut in the grass stems. Billbug grubs hatch about one to three weeks later and begin feeding inside the plant’s stem.

Damage is caused when adults cut into the stem to lay eggs and as they suck out and feed on plant juices. Larvae eat the plant’s stems and roots that are below ground. One of the most likely visible signs of billbug damage are dead spots in the grass that do not “green up” after watering. It is very important to have a pest management professional inspect patches of dead grass to determine what is causing the damage since it can be drought, a grass disease or insects such as billbugs. To inspect for billbug damage, pull up the dead grass; if it easily comes out of the ground it could be billbug larvae damage to the roots. Billbugs commonly damage Kentucky bluegrass, perennial ryegrass and fescue varieties.

More Information

The homeowner should always consult with their pest management professional who will provide insect identification and management help. Pest management professionals can identify the pests that are causing lawn problems, plus provide insight on effective control techniques. Some important techniques for controlling billbugs include:

  • Using turf grass varieties which are resistant to billbugs.
  • Using biological control products such as billbug parasitic nematodes and billbug fungal diseases.
  • Using conventional insecticide control applications during the time of year when they are most effective against the adult and larval billbugs.
  • Using lawn care and mowing methods that minimize the amount of thatch and enhance lawn health. Thatch buildup reduces the movement of water and soil minerals to the plant, plus creates a good habitat for billbug adults to thrive.