In the southeastern United States, the fall armyworm is a pest that is found…in the winter (as well as other parts of the year, lucky us). Right now, yards around central Florida may be experiencing the fall armyworm.
The fall armyworm is a moth (Spodoptera frugiperda) that causes plant damage during the larval phase. Armyworm eggs are small (about 0.4 mm in diameter, 0.3 mm in height) and typically laid in a layer on the surface of leaves. The eggs may exhibit a fuzzy appearance due to the deposits of grayish scales that the female fall armyworm deposits when laying eggs. This stage only lasts a couple of days.
There are six instars (see the photos of the different phases of the fall armyworm here: https://entnemdept.ufl.edu/creatures/field/fall_armyworm.htm) and this larval stage will last from about fourteen days during the summer to thirty days in the winter/colder months.
The pupal stage takes place in the soil and is affected by soil temperature. Prolonged cold periods will result less survival. This stage can last from about eight days in the summer months to about 30 days in the winter/colder months.
Finally, the adults fall armyworm will emerge as a tan moth (measuring about 32-40 mm) with mottled gray and brown forewings. The adult fall armyworm is nocturnal and is most active during warm and humid temperatures.
But what about the damage that fall armyworms cause in the landscape?
Unfortunately, fall armyworms affect a wide range of plant species ranging from field crops to grasses to vegetables and cause chewing damage to leaves. All larvae (caterpillars) have chewing mouthparts, so the damage is obvious. They can defoliate plants and cause damage to growing points (buds) and burrow into plant part (such as in ears of corn).
What can you do if you see damage from fall armyworm?
1. Make sure you have damage from fall armyworm! This means that you should be able to find a caterpillar and make a positive ID. If you are not sure, contact your local UF/IFAS Extension Plant Clinic.
2. Proper plant management is important. Plant early and select vegetable crops that mature early. Scout your garden and be ready to apply a pest management product if needed.
3. There are insecticides labeled for fall armyworms. Bacillus thuringiensis products are effective ad luckily there are numerous natural enemies of the fall armyworm that may help with management in the home garden.
For more information on the fall armyworm: https://edis.ifas.ufl.edu/publication/IN255
For more information, contact UF/IFAS Extension Polk County at (863) 519-1041 or visit us online at http://sfyl.ifas.ufl.edu/polk. The Plant Clinic is open Monday-Friday, 9:00 am-4:00 pm to answer your gardening and landscaping questions. Give us a call or email us at polkmg@ifas.ufl.edu.
If you are not in Polk County, Contact your local UF/IFAS Extension Master Gardener Volunteer Plant Clinic.
The Florida Master Gardener Volunteer Program is a volunteer-driven program that benefits UF/IFAS Extension and the citizens of Florida. The program extends the vision of the University of Florida/Institute of Food and Agricultural Sciences, all the while protecting and sustaining natural resources and environmental systems, enhancing the development of human resources, and improving the quality of human life through the development of knowledge in agricultural, human and natural resources and making that knowledge accessible.
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