Scientific name: Sphenophorus parvulus
Problems they can cause: The Bluegrass Billbug is a major pest of home lawns, often mistaken for other problems due to the difficulty in finding it.
What are Bluegrass Billbugs?
The Bluegrass Billbug is a weevil that in its larval stage attacks lawns anywhere Kentucky Bluegrass is grown.
Signs of Bluegrass Billbugs in your Lawn
Browning of turfgrass along driveways, walkways, streets and near trees that occurs as summer progresses are signs of infestation. In the entirety of the lawn, small brown patches will form that will later coalesce into much larger areas of dead turf are also signs of infestation. While the adult billbug will feed on turfgrass, the damage is negligible. It is the larval stage of the Bluegrass Billbug that is responsible for damage. When eggs hatch, the new larvae will burrow down into the growing point of the turfgrass plant killing it. The larvae resemble white grubs but are smaller and legless. Due to the size and location of the larvae within the plant, Bluegrass Billbug can be very difficult to detect.
How to Prevent & Control Bluegrass Billbugs
A lawn that has a confirmed history of Bluegrass Billbug should have a surface insect control product applied targeting the overwintering adults as they emerge in the spring when temperatures are above 60 degrees and travel near warm surfaces like black asphalt driveways. The preventive products that are applied for control of white grubs will coincidently be effective for Bluegrass Billbug; however, the problem here lies in the timing. The proper timing for preventive control of Bluegrass Billbug is prior to that for White Grubs, so there exists the possibility that some Bluegrass Billbugs will escape control.
How to Repair Lawn Damage from Bluegrass Billbugs
Light infestations can be masked with additional fertilization and irrigation but when populations are high there will be significant turf loss. Core Aeration and overseeding are recommended in late summer and early fall with both resistant cultivars of bluegrass, ryegrasses and fescues, but also with turf-type tall fescue, a species that is resistant.
Bluegrass Billbug is not something that a homeowner can detect easily. It is better left to a professional that has been trained and has experience in finding them. Proper identification is key to ensuring that any control products applied are used properly.