Pest of the Week - Cereal Leaf Beetle

The pest of the week is the Cereal Leaf Beetle(Oulema melanopus Coleoptera: Chrysomelidae). Before we talk about the Cereal Leaf Beetle, let us take a look at the beetle family.  Beetles are the most common type of insect.  Beetles are everywhere.  But beetles can be confused with other kinds of insects, especially some true bugs.  So how do you recognize a beetle?

First look for the wings and wing covers.  Most insects have wings, and those that do have two pairs.  Beetles differ from all other winged insects by having the first pair of wings hardened and thickened.  These hard forewings serve as a protective shield for the fragile flying wings, which are folded underneath. The Latin name for this order, Coleoptera, means “folded wing”.  Wing covers in beetles meet in a straight line down the middle of the back  

The Cereal Leaf Beetle adult is about 1/4 inch long with a bright orange thorax and blueish metallic head and wing covers.

Adult Cereal Leaf Beetle

 

The first sign of Cereal Leaf Beetle activity in the spring is adult feeding damage on the plant foliage. Adult injury to the plant is characterized by elongated, slender slits in the upper leaf surface.

Damaged wheat leaves and larvae (Purdue University)

While this is the first sign of infestation, it is Cereal Leaf Beetle larvae that are the target of control. Eggs and larvae are monitored by inspecting individual plants.  Thresholds are expressed as egg and larval numbers per plant or per stem.
The boot stage is a critical point in wheat plant development.  When the flag leaf emerges, feeding is generally restricted to the flag leaf. Damage to this leaf can significantly reduce grain yield and quality.  At the boot stage, the threshold is one larvae or more per flag leaf.

The Feekes scale of wheat development

Lady beetles prey on Cereal Leaf Beetle larvae. Several imported parasitic insects attack Cereal Leaf beetles.  The parasites imported from overseas and established in some areas of the U.S. include Anaphes flavipes, a wasp that parasitizes Cereal Leaf Beetle eggs

Additional Information

Bug Club Identification Key - University of Florida

InsectID: Beetles - UW-Madison

Cereal Leaf Beetle Biology and Management - Virginia Tech

Growth Stages of Wheat - Texas A&M Extension

Growth and development guide for spring wheat - University of Minnesota