Grubs in Pastures

May 2009

It had to happen. Grubs have been a turf grass problem for years and now grubs are becoming more common in pasture grasses as well. Many counties in eastern and central Nebraska have reported finding grubs in scattered areas within pastures over the past several years.

Most of the time grubs have been found in pasture areas dominated by bluegrass, which seems logical since they also like bluegrass lawns.

An interesting feature of the pasture grubs, though, is that University of Nebraska entomologists discovered that many of the grubs in pastures belong to an entirely different genus of grubs than those commonly found in lawns. This unusual genus has not been studied very thoroughly so their life cycle is unknown.

Since grubs have been found in pastures during all months of the growing season, they may be like the May/June Beetle, which has a three-year life cycle that includes about 24 months as a grub. This is just my speculation, though.

The big question is how do we control these grubs? At this point, we don't know. Skunks, birds, and other animals like to dig up the grubs for food, leaving a pasture full of unproductive divots. Sevin is the only chemical labeled for pastures that can kill grub larvae but it's not very effective in a pasture environment. Other pasture insecticides are likely effective only on adults, not on the grubs.

My best recommendation for now is to have grasses more productive than bluegrass in your pasture and keep them healthy and vigorous with good management. Grub problems probably are here to stay. We may need to learn to live with it.

Dr. Bruce Anderson, Professor of Agronomy
Agronomy & Horticulture, University of Nebraska–Lincoln, Lincoln, NE