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Armyworms Wage War Via Guerrilla Warfare

Armyworms Wage War Via Guerrilla Warfare

Armyworms come in a wide range of colors and sizes.  A few of the prominent species living in Florida are beet, southern, and fall armyworms.  And the term “living” is not an exaggeration,  because Florida is one of the lucky states where it is warm enough for armyworms to overwinter.  They are the snowbirds that never leave!

Armyworm damage in turf.

Armyworm damage on a lawn. Credit: Purdue University

Armyworms are notorious for unanticipated invasions.  They feed on most turfgrass species and most vegetable crops, but they prefer grassy vegetable crops such as corn.  Armyworms feed in large groups and their feeding has been described as “ground moving” in lawns. They feed during cooler times of the day (morning and evening) and they roll up and rest under the vegetative canopy (in the thatch layer in turf and in the base of leaves in vegetables) during the heat of the day.

Armyworms are difficult to control because of their spontaneity.  However, in the lawn they hide in the thatch during the heat of the day.  Over watering and fertilization can increase the amount of thatch.  It is important to follow UF/IFAS guidelines for home lawn management.  A good weed control program can also help to deter armyworms, because weeds serve as an alternate food source.

Numerous chemical control options are available, but softer chemicals such as horticultural oils and insecticides containing the bacteria Bacillus thuringiensis are recommended as a first line of defense.  Insecticides should be applied in the morning or evening during feeding time.  For additional control strategies and basic information please visit the UF/IFAS Armyworm Publication Page.

Armyworm damage on corn.

Armyworm feeding on a young corn plant. Credit: University of Illinois

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Author: Matt Lollar – mlollar@ufl.edu

Matt Lollar is the Jackson County Horticulture Agent. He has 5 years of experience with University of Florida/IFAS Extension and he began his career in Sanford, FL as the Seminole County Horticulture Agent. Matt is originally from Belle Fontaine, AL. He earned his MS and BS degrees in Horticulture Production from Auburn University.

Matt Lollar

Permanent link to this article: http://okaloosa.ifas.ufl.edu/newsletters/2015/09/23/armyworms-wage-war-via-guerrilla-warfare/