Ontario Cereal Leaf Beetle Survey

This article was written by Tracey Baute, Entomologist- Field Crops and Joanna Follings, Cereals Specialist

Cereal Leaf Beetle (CLB) is an important pest in cereal crop production feeding on wheat, oats, barley, corn, forages and grassy weeds. CLB overwinters as an adult and then emerges early in the spring and females lay their eggs on leaves in wheat fields and grassy weeds (Figure 1). The eggs usually hatch by mid-May and the larvae (Figure 2) feed for two to three weeks before pupating and turning into adults (Figure 3) by mid-June. These adults will continue to feed on wheat but can also move to corn fields and feed for a short period before going dormant for the rest of the summer. In the fall the adults then move to overwintering sites. The larvae and the adults cause damage by chewing tissue between leaf veins causing that window-paining effect.  When feeding damage is severe, fields will almost look silver as you pass by them. Yield losses in winter wheat of 30% or higher have been reported in both Canada and the US with even higher losses reported in spring cereals.

Figure 1: CLB egg masses on upper surface of cereal or grass leaf.  Photo: Susan Gowan
Figure 2: CLB larvae feeding on cereal leaf and causing that window-paining effect. Photo: Tracey Baute
Figure 3: CLB adult emerges by mid-June. Photo: Jocelyn Smith

In Ontario, CLB has historically been a challenge in smaller pockets around Dresden, Bolton, Stayner, Seaforth and Clinton; however, there is anecdotal evidence that this pest may becoming more of an issue in other parts of the province. They have also been observed more frequently in Ontario Cereal Crop Committee (OCCC) trial locations.

As a result, we are looking to collect as much baseline information as possible this growing season on where and when this pest emerges in the province to help us better track it.  We have also selected a number of locations across the province where we will scout fields and/or plots weekly to track both crop stage and CLB emergence and staging. This information will then be used to help validate models developed by Agriculture and Agri-food Canada that can help predict CLB life stages and can improve our scouting guidelines for this pest.

To help us get the most information possible, we are asking for your help!  If you are out scouting cereal fields this growing season and come across CLB, we want you to let us know where you are finding this pest and at what levels, along with some basic field information. To enter your field information, please complete the CLB survey at the following link: Cereal Leaf Beetle Survey. The survey can be accessed from your smartphone, tablet or you can enter the field location information at your desktop computer.

If you are finding this pest, control may be warranted if an average of 3 larvae per tiller are found before boot stage or 1 adult or larvae per stem warrants control after boot but prior to heading. If significant feeding is taking place on the flag leaf in the early heading stages, control may be warranted.

For more information on CLB staging please check out: https://fieldcropnews.com/wp-content/uploads/2020/04/Cereal-Leaf-Beetle-Life-Stages.pdf

For information on cereal crop growth stages please check out:  http://coolbean.info/wp-content/uploads/sites/3/2018/04/2018_WheatGrowthStages_FINAL.pdf

For information on how to complete the survey please check out the  Instructions for Collecting Cereal Leaf Beetle Counts