Your customers may be wondering why in the world their lawns have “brown” patches in them. Unfortunately, until a thorough inspection is complete, the reason may be due to armyworms. 

Armyworms have been particularly heavy this season in Texas along with several other states.

Let’s look at some facts on these little “lawn-munching” caterpillars and some ways to possibly treat them.

Armyworm Facts

This lawn and garden pest gets its name because it moves in miniature “insect armies” and eats almost everything in its path. 

Armyworm caterpillars come in various types, each with a particular liking for a specific plant or food. However, some will eat anything green, red, or yellow. They are primarily active at night and hide throughout the day among plants and in the soil.

Armyworms attack many crops and grass types and move throughout the region in masses that resemble a “marching army.” Armyworms result from the larval life stage of grey “spotted” moths, which generally migrate in darkness to lay eggs. The largest armyworm invasion happens typically after a wet, rainy spring.

Armyworm Identification

Markings on these newborn caterpillars are often challenging to see, while older ones have prominent stripes along the length of their bodies. Now, “beet” armyworms are green with light lines, while “fall” armyworms are brown with yellow stripes.

Adult armyworms originate from grey, spotty moths with a tiny white dot in the middle of each forewing and black borders on the hind wings with a 

1.5-inch wingspan.

Armyworm Life Cycle

Armyworm moths are abundant and adaptable in their surroundings. First, they deposit their eggs in mounds on larger plant leaves. Then these “miniature” caterpillars hatch in 5-10 days and eat for several weeks. After that, they pupate or transform and emerge as adults ten days later.

Each season, three or more generations of armyworms turn up.  So, while one generation is ready to move on or eliminated, another generation is getting ready to replace them in the soil. Also, certain armyworm species may lay up to six times in one season.

During the colder months, armyworms typically look to migrate beneath the soil into areas with warmer winters, like southern states. Some armyworm species may be active all year in warmer climates.

Damage

Little brown patches of grass are usually the first sign of an armyworm infestation. These lawn-destroying insects will rip the grass blades or nibble the green outer covering, resulting in an “outline” appearance.

So, keep in mind not to mow the grass too low during this armyworm infestation, or you will have significant, barren patches on the lawn. Also, these “micro-munchers” will chew up similar patterns of holes on other plants with larger leaves.

Armyworm Control

Early morning and late evening are the busiest times for the armyworm larvae. Therefore, to get the best extermination results, you should align your treatments with this activity, using chemical pesticides or insecticides.

You can treat an armyworm infestation with a variety of insecticides and pesticides, including some that are non-toxic alternatives that won’t harm other beneficial insects and pollinators but are a great choice. The following are the most prevalent chemical treatments and techniques for armyworms:

•   Bifenthrin The armyworm’s nervous system will be paralyzed when ingested by this toxic insecticide. However, it is a residual chemical so it may take several days before you see the effects taking place. Warning: The EPA has classified this as Toxicity Class 2, so it tends to kill other insects and bugs as well.
•   Bacillus Thuringiensis (BT) The armyworm’s digestive system will be paralyzed by this bacterium. However, pollinators and birds will be unaffected. You can spray this on diseased grasses in liquid form.
•  Pyrethrin Pyrethroids are natural insecticides produced from crushed dried flowers and water that paralyze armyworms when they ingest them but leave other insects alone.
•   Neem Oil This natural insecticide, made from neem leaf extract, kills armyworms without using hazardous chemicals.
•   Diatomaceous EarthThis insecticide contains tiny dust particles are like crawling over sharp blades to the armyworms, yet they are safe for pollinators and animals.

Now, if you so choose, you can also pull armyworm larvae from their host grass by hand and destroy them in a basin of soapy water for a more restricted invasion. Do not forget to wash your lawn service tools.

Armyworm Prevention

To prevent armyworms from launching a second attack, follow optimal lawn care techniques. Maintain excellent lawn care practices such as regular lawn mowing, thatch reduction, and moderate irrigation. Healthy grass will be able to survive modest armyworm infestations.

Here are some steps to keep in mind for a healthy lawn when “combatting” armyworms. 

• Aerate the lawn once a year. To reduce thatch accumulation, which can host armyworm grubs, add about a quarter inch of organic materials like peat moss.
• Water the lawn regularly. Armyworms enjoy a dry, warm environment. A well-watered yard keeps the soil surface colder, which deters the armyworms.
• Keep weeds and wild grasses to a minimum and mow the lawn no shorter than two inches.
• Regularly inspect for armyworms and grubs. It is easier to cure an infestation if discovered early.

Armyworms are devastating pests that eat grass, but they will eat vegetables and other plants when food is short. When there are many armyworms on the lawn, they might look like an army unit marching side by side. Infestations may kill lawn grasses in a matter of days.

Therefore, armyworms are bad news for your customer’s lawns, and as soon as you can identify them and treat them, the better. You may need a license to be fully compliant in using insecticides and pesticides in treating armyworms, so check with your local city ordinances first on these requirements. 

However, pest control services for your lawn care business are a great way to make additional income, and you will be the hero when it comes to saving your customer’s lawns from an armyworm infestation.