What the Heck Is That?!?!

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Spring is upon us and plants are starting to green. If you look closely in wheat fields this time of year you may see adults of this insect laying eggs. These eggs will then hatch and feed on the crop in the upcoming months, becoming an agricultural pest. Do you think you know what insect larvae is being described and is depicted below? Test your expertise with this installment of “What the Heck is That?!?!”

Larvae of this insect are identified by the plants on which they feed: wheat, barley, rye, and other grains. If that helped you guess cereal leaf beetle you are correct! Cereal leaf beetle adults (image below) have metallic black heads and elytra (wing covers) with a bright red thorax. Adults emerge from leaf litter in the woods and woods’ edges from March through April to lay eggs in adjacent grain fields. These eggs will then hatch and can become pests of the grains on which they feed.

Larval cereal leaf beetles are yellow to orange in color and appear similar to slugs. This color is often darkened by a layer of feces and mucus, giving them a shiny appearance (quiz image). One method to determine if larvae are present in a field is to walk through a field with light colored pants. If there are larvae in the field, your pants will become covered with the larvae’s waste. Remember to only wear an old pair of pants when you are scouting for this pest!

Older larvae are voracious feeders that can cause extensive damage. Cereal leaf beetle damage is characterized as streaks of yellowing leaf material caused by the larvae scrapping the leaf tissue when feeding. Fortunately, control of this pest is not often needed here in North Carolina. The number of larvae present to warrant insecticide application threshold is four larvae per one wheat tiller. Wheat planted early in the season is usually safe from injury levels that will reduce farmer’s yield.

adult cereal wheat beetle

Photo by Judy Gallagher

You can also view this fact sheet for more information on cereal leaf beetles.   If you have content (images, ideas, etc.) you would like to have featured in the upcoming installments of “What the Heck is That?!?!” email or call Adam Formella at adam_formella@ncsu.edu or 252-232-2262.