Billbugs in Denver

Billbugs Are Making a Strong Appearance This Year in the Denver Metro Area:

Adult Billbug

Adult Billbug

Over the last few years Bill bugs have not been a huge problem. They were around, but there were few reported cases of large amounts of Billbug damage in lawns.

However, this year several areas are seeing a resurgence of this lawn pest. Damage tends to start at the edges of the lawn, by sidewalks and patios then moves deeper into the lawn. Damage along edges tends to be more consistent than damage deeper into the yards. This leads to brown edges and a more splotchy appearance deeper into the center of the lawn. In many cases damage is limited to edges only which gives an almost ‘mite damage”. Another common misdiagnosis, since the damage is usually is evident along the edges of paved areas, is salt or mag chloride damage (except billbug damage normally appears in July). Eventually the damage may spread throughout the turf expanse. The primary difference is, the grass is not straw colored, dry and crunchy, but brown and can be easily pulled up.

Billbug Grub Size

Billbug Grub Size

Finding the small Billbug grubs can be difficult. They are an off-white color with a brown head, but extremely small. It is not uncommon for people to think a Billbug grub is a large chunk of sand and dismiss it.

Insect control will cut down on further damage, but the full extent of the initial damage my still not be seen for a week or more after a proper insect control treatment is given.

Background on Billbugs:

Note the Brown Head

Note the Brown Head

Billbugs completes one generation per year. Billbugs overwinter as adults in semi-protected areas (in surface litter around buildings, in leaf litter, or in hedgerows). Adults emerge during the first warm periods in the spring and begin to move to suitable turf sites. Adults can be observed crossing paved areas on sunny days in May through early June.

The adult females lay eggs in May and June, which hatch into small larvae and feed within the grass stems for about two weeks. As they grow, they molt and move to the bases of plants, where they feed on the crowns. Eventually they also feed on roots and rhizomes.

Frass Along the Root

Frass Along the Root

In areas where bluegrass billbug larvae have been feeding actively, there will be accumulations of “frass,” or insect excrement, which is white and has the texture of fine sawdust. The “frass” serves as positive identification of bluegrass billbug damage. Larvae continue to feed for most of the summer and then pass through a brief pupa (“resting”) stage in the soil in late August. Young adults then emerge and seek out suitable overwintering sites during September and October. Thus the primary period for damage is in July and most of August, while the larvae are actively feeding.

If you suspect Billbugs or other insect activity, please contact Mountain High Tree, Lawn and Landscape for a free Lawn Evaluation: 303-232-0666