Cereals: Cereal Leaf Beetle

Excerpt from Agronomy Guide for Field Crops (Chapter 6)

Order OMAFRA Publication 811: Agronomy Guide for Field Crop

Table Of Contents

1. Description
2. Life History
3. Damage
4. Scouting Technique
5. Action Thresholds
6. Management Strategies
7. Updates on Cereals: Cereal Leaf Beetle
8. Related links...

Description

The cereal leaf beetle (CLB) adult is a metallic, blue-green beetle, approximately 0.5 cm in length, with a reddish-orange head and legs. The larvae are 0.6 cm in length when mature and yellowish in colour, but this colour is obscured by a black deposit of fecal material making it slug-like in appearance.

Plate 106. Cereal leaf beetle larvae are yellowish, but this colour is obscured by a black deposit of fecal material making it slug-like in appearance.

| Top of Page |

Life History

CLBs overwinter as adults in leaf litter in sheltered areas such as woodlots and heavy crop debris. These adults emerge in early spring, and the mated females then lay their eggs in wheat fields on the upper surface of the leaves. The eggs hatch, and larvae are present by mid-May. The larvae will pupate, and adults will emerge by mid-June. Adults feed on wheat briefly and then congregate in corn fields, feeding for a short period before going dormant until fall. In the fall, adults become active again and make their way to their overwintering sites. There is one generation per year.

Damage

Cereal leaf beetles feed on wheat, oats, corn, forages and grassy weeds. Both adults and larvae cause damage by chewing long strips of tissue between the leaf veins, leaving the top layer of the leaf intact. This creates a window-paning or "skeletonizing" effect. Most of the injury is caused by the larvae in June. Heavily damaged fields appear silver.

Scouting Technique

Begin scouting in late April. Examine 20 plants in five locations across the field. It is important to scout various areas of the field, as CLB tends to be unevenly distributed across the field. Record the number of beetles and larvae found per plant. Scout every 5 days, as damage can increase dramatically within days.

| Top of Page |

Action Thresholds

One CLB adult or larvae per stem warrants control, especially in the earlier stages of the crop (before heading).

Management Strategies

An insecticide may be necessary when the threshold has been reached. See OMAFRA Publication 812, Field Crop Protection Guide, for insecticide recommendations. This pest is mainly controlled by natural enemies where reduced tillage is practised. Clean plowing increases the risk of this pest, because the overwintering sites of the parasites are destroyed. In some parts of Ontario with mild winters or tobacco production (where plowing is practised), the parasites have been less effective. (Order OMAFRA Publication 812)

| Top of Page |

Updates on Cereals: Cereal Leaf Beetle

• Field Crop Protection Guide - Publication 812
  • Cereals: Cereal Leaf Beetle

Related links...

• Insects
• Cereals

| Top of Page |