Dark/Yellow Mealworms - School IPM - USU Extension

    Dark/Yellow Mealworms

    Tenebrio spp.

    Dark Mealworm

    Top: Dark mealworm (Clemson University, Bugwood.org)  Bottom: Dark mealworm adult (Pest and Diseases Image Library, Bugwood.org)

    yellow mealworm

    Top: Yellow mealworm adult; Bottom: Yellow mealworm (Clemson University, Bugwood.org)


    Dark mealworm

    • adult: dull black or very dark brown
    • larvae: up to 1 1/4 inches long, smooth, cylindrical and brownish to dark yellow

    Yellow mealworm

    • adult: shiny black to dark brown
    • larvae: up to 1 1/4 inches long; smooth, cylindrical and golden-yellow 

    Nesting Habits

    • lay eggs singly or in clusters in food sources
    • prefer dark, damp and undisturbed environments
    • larvae can migrate from infested areas


    • old or moldy grain, oats or seeds


    • presence indicates a lack of proper sanitation
    • eggs and/or larvae ingested with breakfast foods can cause gastrointestinal discomfort

    IPM Recommendations

    • Improve sanitation procedures in affected areas.
    • Inspect all incoming food items for pests.
    • Store food items in pest-proof containers. 
    • Dispose of infested food items.
    • Keep moisture low in food storage areas by improving ventilation.
    • Keep food in regular rotation.

    Additional Resources

    IPM for Fabric and Pantry Pests: Integrated Pest Management in Sensitive Environments (University of Nebraska-Lincoln Extension)