Army Worms

There has been a severe outbreak of Fall Armyworms all across West Tennessee lately and here are some interesting facts about this unwanted pest.

armywormArmy worms are stout-bodied, hairless, striped caterpillars that chew on the foliage of grass. They are named because of their habit of crawling in large numbers from field to field when they have exhausted their food supply. Several species of armyworms attack turfgrass. Homeowners are understandably concerned when their turf is literally mowed down by a mowing “army” of caterpillars that seems to appear overnight. There are three major species of armyworms that attack turf in the U.S.  Fall armyworms cause more damage over a broader area.  These destructive pests can eliminate your plants or turfgrass  in less than 1 day. People will say “I’m going to let the worms cycle through because most are pretty big.” This is usually a mistake because a larva will consume over 80% of its total food needs in the last few days before it pupates. First generation caterpillars cause the most damage in an area but can be prevented.

A little info about their lifecycle:  Armyworms spend the winter as mature lavae or in a pupal stage amid plant debris or down in the soil itself. As the name indicates fall armyworms are most numerous in late summer or early fall. On certain occasions with severe outbreaks, armyworms can occur as early as mid-April. It is in this feeding period that the larvae cause the most destruction. After pupating, they will emerge as moths ready to mate, lay eggs, and continue their cycle. There can be anywhere from 2-3 generations per year, with some areas having 4 if the conditions are favorable. Fall armyworms are typically most active early in the morning, late afternoon, or early in the evening, but on taller grass, can be observed feeding throughout the day. They feed and destroy crops and since the majority of this activity is done at night, they are often hard to discover before extensive damage has already been done. When they have devoured a field or your lawn, they will move together to a new area with fresh food. Armyworms pass the winter in partially grown larvae in the soil or under debris in grassy areas. Activity and growth are continuous except during VERY cold weather.

Armyworm damage proceeds at a faster rate because of the large sized caterpillars, synchronous egg laying, and subsequent population growth. 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 any given lawn. Fall armyworm moths usually fly between the hours from dusk til dawn. If you see clouds of moths, with a wingspan of about an inch, check your lawn 7-10 days later for fall armyworms. Insecticides with longer residuals are a better choice for outbreak years. An application of insecticide may be necessary if the infestation is extremely severe and/or the plants are under stress.


Pyrethroid insecticides generally provide excellent control of Fall Armyworms. Call us today if you have any questions or want to get this service scheduled.

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