Crop & Pest Report


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Insect Sampling in Turfgrass (06/27/19)

Before resorting to pesticidal sprays, it is important to know what is causing the issue in your lawn.

Before resorting to pesticidal sprays, it is important to know what is causing the issue in your lawn. While diseases may first come to mind, insects are just as often the issue. Turfgrass insects can be extremely destructive to residential lawns. There are many insects which can damage lawns in North Dakota and the Red River Valley, including chinch bugs, grubs, and the larval stages of many moth species. Some may only be present for a short time, yet their damage can be an eyesore well into summer. Sampling is necessary to detect and estimate the number of insects present in a given area and determine if chemical control is needed.

The following are reliable sampling methods for determining pest populations of turfgrass insects commonly found in North Dakota:

Flotation sampling — Cut both ends out of a metal cylinder such as a coffee can. Pound it 3 to 4 inches into the ground in a damaged area and fill it with water. Small insects will float to the top quickly. Estimate the number of insects per square foot based on the number present in the area covered by the can.

Irritant sampling — Mow the grass in the damaged area. Then, mix 2 tablespoons of liquid dishwashing detergent in 2 gallons of water and pour the entire batch over 1 square yard. Any larvae present in the canopy should come to the surface in a few minutes.

Soil sampling — Cut a square foot of turf on three sides, undercutting 2 to 3 inches deep with a sharp, flat-edge shovel. Roll the sod back and count the number of grubs in the sampling area. Crumble some of the soil from the root zone to expose more grubs. After counting, level the soil and roll the sod back into place. Be sure to provide water for several days to promote re-establishment. Roots should recover quickly if the sample was cut deeply enough.


The most common turfgrass insect pests are listed in the table below with their appropriate sampling method and respective thresholds. Control is not advised If there are fewer insects found than the presented threshold.


For questions about identifying and managing turfgrass pests, please call the Plant Diagnostic Lab at 701-231-7854. Adapted from extension publication H-1553, Home Lawn Problems and Solutions for North Dakota.

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Alexander Knudson

Entomological Diagnostician

NDSU Extension Plant Diagnostic Lab

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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