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Fall armyworms are subtropical insects. In mild winters, a few may survive in southern Alabama and Florida. In North Alabama, They die out after the first hard frost. Each spring, moths fly northward from overwintering grounds in Florida, the Caribbean islands, and possibly southern Texas. The first moths fly into Southern Alabama in April. Later generations work their way north reaching North Alabama by May. Throughout the summer, local populations of fall armyworms are increased by flights of moths from further South.

Fall armyworm damage tends to occur in short intervals that are about a month apart. Why? It takes approximately one month from the time a fall armyworm moth lays an egg to the time her daughters lay their first eggs. This is all dependent on temperature, of course, since insects are cold blooded. The warmer it is the shorter this generation time. But as a general rule of thumb, in the middle of the
summer:

Eggs hatch in two to four days
Caterpillars feed for about two weeks, during which time they pass through six growth periods (instars)

Caterpillars transform into moths during the pupal stage, which lasts about nine days
Adult moths live for about two weeks, but females lay most of their eggs four to nine days after they emerge from the pupal stage.

In epidemic years, the generations of fall armyworms overlap, allowing for almost continuous egg laying, which means that caterpillars of all sizes can be found in a given field. In epidemic years, the monthly intervals when most of the damage occurs are not as noticeable. The first damage from fall armyworms is often seen in the same area of the field as in previous years. This is because the female moths are choosy about where they lay their eggs. Some of their favorite places to deposit a mass of eggs are: the underside of fence rails, the underside of tree branches, and lush, well fertilized forage such as bermudagrass and browntop millet. So if you usually see the first brown spots occurring in your best hayfield, under the limbs of the big oak
tree, now you know why. Experience in where fall armyworms are first found can help you find the caterpillars before they cause problems.

Bermudagrass Stem Maggot Publication: https://www.aces.edu/wp-content/uploads/2019/06/ANR-1462-Biology-and-Management-of-Bermudagrass-Stem-Maggot_061319.pdf

Bermudagrass Stem Maggots have been migrating North to North Alabama since 2010ish. We first discovered them in Cherokee County In 2012. They usually reach our area by July 1 and cause damage to Bermudagrass until first frost. They fly lays eggs on the stems and the maggot grows inside the stem stopping the growth of the plant. The life cycle is 21 days and multiple generations are possible. The best control method once damage is found is to cut the field, spray 5 days later or at green up. Remember you are targeting the fly with a pyrethroid. There is not a systemic available to try and control the maggot. The flies are small and hard to see using a sweep net. Blue sticky traps work well to trap them and bring them in to the office to observe under a microscope.

Controlling both Pests: Please refer to the Alabama IPM Guide: https://www.aces.edu/wp-content/uploads/2019/02/IPM-0028_PastureForageCrops_011018L-copy.pdf to select pest management strategies for your situation remember to read the label properly because there are some products used when pests are smaller than a certain size for Fall Armyworms. There are different modes of action with different products.

If you have questions feel free to give me a call at 256-706-0032. Please report to your County Extension Office for pests in the area.

Thanks,

M. Landon Marks
Regional Extension Agent | Animal Science and Forages
Alabama Cooperative Extension - Sand Mountain
1526 Chesnut Bypass
Centre, AL 35960
(256) 706-0032 | mlm0013@auburn.edu