European Corn Borer

Ostrinia nubilalis

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european corn borer inside corn European corn borer larva inside corn.

mature european corn borer
Mature European corn borer larva.

recently hatched european corn borer larvae on leaf Recently hatched European corn borer larvae.

European corn borer pupa
European corn borer pupa.

Two european corn borer adultsEuropean corn borer adults.

Hosts

  • Field-grown hemp
  • Corn
  • Peppers
  • Potato
  • Snap beans
  • Various ornamentals

Description

Larvae are creamy-white to gray with one row of small, round, brown spots in each body segment. Adults range in color from pale yellow-brown to light brown to dark brown with wavy markings on the wings. Eggs are clear-white and are laid in flat masses on the undersides of leaves. 

Life Cycle

Egg | Larva | Pupa | Adult

  • Likely 2-3 generations per year in Utah.
  • Overwinter as caterpillars in stalks and debris of host plants.
  • Pupation occurs inside stems.
  • Adults fly from May-June (first generation) and in July-August (second generation).
  • Eggs are laid in flat masses on the undersides of leaves.
  • Young larvae feed on leaves, then bore into the stem to complete the life cycle.

Damaging Lifestage(s): Larva

Damage Symptoms

Newly hatched larvae feed in leaf whorls and then bore into the stems. Symptoms include significant structural damage along with wilting, dieback, and reduction of  yield. 

Time for Concern

Spring through harvest.

When and Where to Scout

  • Monitor for adult moths in May-June and July-August using a pheromone trap.
  • Adult moths indicate the need to scout for egg masses on plants.
  • Look for egg masses laid on leaves, larvae inside stems, and damage symptoms such as plant wilting and dieback.

Threat Level

Medium if established.

Occurrence in Utah

This insect has not been identified as a pest in Utah hemp. 

Management

  • Remove overwintering larvae by removing crop debris, including stems and stalks.
  • Management with insecticides can be difficult for this pest. 

When to Consider Treatment

If there is a high population of moths and the signs of damage are seen consistently.

Look-alikes

None.

Caterpillar Insecticides

Utah-Registered Product Active Ingredient(s) Notes
Agree WG Bacillus thuringiensis ssp. aizawa  
Aza-Direct Biological Insecticide azadirachtin  
AzaGuard  azadirachtin  
AzaSol azadirachtin  
Azatin O Biological Insecticide azadirachtin  
Azatrol EC Insecticide azadirachtin  
Azera Insecticide azadirachtin  
BT Now Bacillus thuringiensis ssp. kurstaki Greenhouse use only.
Bug Buster-O Extinguish Ant Bait pyrethrins Greenhouse use only.
Deadzone diatomaceous earth  
Deliver Biological Insecticide Bacillus thuringiensis ssp. kurstaki  
DiPel DF Biological Insecticide Bacillus thuringiensis ssp. kurstaki  
DiPel DF Biological Insecticide Dry
Flowable		 Bacillus thuringiensis ssp. kurstaki  
DiPel PRO DF Biological Insecticide Bacillus thuringiensis ssp. kurstaki  
Evergreen Crop Protection EC 60-6 pyrethrins  
Ferti-Lome Dipel Dust Biological Insecticide (RTU) Bacillus thuringiensis ssp. kurstaki  
Ferti-lome Fruit Tree Spray pyrethrins  
Grandevo CG;WDG Chromobacterium sub strain PRAA4-1 cells  
Javelin WG Biological Insecticide Bacillus thuringiensis ssp. kurstaki  
Leprotec Bacillus thuringiensis ssp. kurstaki  
Molt-X azadirachtin  
Neemix 4.5 Insect Growth Regulator azadirachtin  
Prizefighter ammonium nonanoate  
Pycana  pyrethrins Greenhouse use only.
Pyganic Crop Protection EC 1.4 II; 5.0 II pyrethrins  
SPEAR-LEP gs-omega/kappahxtx-hv1a Supression only; combine with a Bt product for greater efficacy.
Tersus Insecticide pyrethrins  
Thuricide N/G Bacillus thuringiensis ssp. kurstaki  
Valent Professional Products DiPel Pro DF Biological Insecticide Dry
Flowable		 Bacillus thuringiensis ssp. kurstaki  
Venerate CG Burkholderia sp. strain A396  
XenTari Biological Insecticide Dry Flowable Bacillus thuringiensis ssp. aizawai  

Photo Credits

  • Larva in stem/Adults - Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
  • Mature larva - Mariusz Sobieski, Bugwood.org
  • Recently hatched - Phil Sloderbeck, Kansas State University, Bugwood.org
  • Pupa - Frank Peairs, Colorado State University, Bugwood.org
Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.