Armyworms are prolific and sensitive to favorable conditions. Their eggs are laid in fluffy large clusters on the crowns of seedlings and on the leaves of older plants. In five to ten days, the caterpillars hatch and feed for several weeks. As they pupate, they emerge as adults 10 days later. More than three generations are commonly produced every season while you’re taking care of worms from your garden plants. One generation may also lay six eggs in a single season if they are not able to escape. It is thought that armyworms will overwinter as eggs and pupae below the soil in places with milder winters. In warm climates, they may remain active all year round.
There are several species of armyworm caterpillars, many with specific tastes for specific plants and vegetables, however, others will eat foods like anything green or red, or yellow. Most active during the night, they hide under plant leaves and behind weeds during the day. It is primarily found in the southern part of the United States, where it thrives on turf lawns such as Bermudagrass and infests them, causing moderate to severe damage. In the case of Armyworm infestation, it may appear as brown grass, which novice gardeners assume is the result of the grass not getting enough sunlight or water. However, what is actually happening is Armyworms are eating blades of grass, depleting them of their nutrients.
The armyworm can damage lettuce seedlings by feeding in the crown and eating off the midrib and growing point. Once heads are formed, the caterpillars can devour them, rendering them difficult to market. Its larval stage attacks a variety of crops as well as grasses, sometimes spreading to a new location in an attack that is mostly aerial. The moths usually arrive in darkness that day to lay eggs. During a cool, humid spring the most widespread attack occurs.
A fully-grown larva is approximately 1 to 1.5 inches long and bears a series of green, yellow, or brown stripes along the length of its body. During its early development stages, they can be either light green or tan, and darker in later stages.
Usually Army Worms have brown to light brown head capsules with a Y-shaped morphology. The activity of Army Worms is mainly from Summer through early Fall. On newly hatchled caterpillars, there is usually no distinct pattern, older larvae have distinct stripes that run the length of their body. Fall armyworms are brown with yellow stripes, beet armyworms are green with light stripes. A gray, mottled moth, with a 1- 1/2 inch wingspan, presents two small white dots on the forewings.
Products and Procedure for Armyworm Control
A pesticide application may be economically justified when 75% of plants exhibit leaf feeding or the larvae are less than 1.25 inches long (University of Missouri). There is no efficacy of treatment inside the ears.
Among the best insecticides to treat Armyworm infestations is a combination of Bifen LP and Reclaim IT. These products are labeled for Armyworm control and deliver a powerful punch, providing superior surface and subsurface control and avoiding the entire infestation.
Step 1 – Apply Bifen LP Granules to Lawn
Bifen LP is a granular pesticide for controlling many pests, including armyworms. To calculate your lawn’s square footage start by measuring its length and width in feet, then multiplying them (length x width = square footage).
Apply Bifen LP granules at a rate of 1.15 pounds per 1,000 square feet to treat this worm infestation. Spread the granules using a push broadcast spreader, or by hand for smaller patches of lawn.
Put the proper amount of Bifen granules into your spreader based on the square footage of your property. Distribute half of the granules evenly, once across the area, and the other half parallel to it. Once you have applied Bifen LP, it will need to be diluted in order to activate it. This will be done with Reclaim IT in the next step.
Step 2 – Mix and Apply Reclaim IT to Lawn
It also kills Armyworms exposed to the product and delivers long-lasting residual action that continues to kill up to 90 days after application. Reclaim IT is a broad-spectrum insecticide that is specifically labeled for treating Armyworms. To apply reclaimed IT, mix water in a hand pump or hose-end sprayer and apply .18 to .25 fl. oz. per gallon, according to the directions on the bottle.
It is often recommended to use a 20-gallon hose-end sprayer so that a broad application of the product can be made throughout the entire lawn. Attach the hose-end sprayer nozzle to the hose and ensure the control valve and water pump are turned off. Remove the reservoir from the nozzle and add the proper amount of Reclaim IT and water to the hose.
Once the product has been added to the reservoir, plan on using 2 gallons of water for every 1,000 square feet. Reattach the reservoir to the nozzle securely, and then start spraying by pushing forward on the control valve after the water has been turned on.
Rather than spot treating, distribute the Reclaim IT evenly over the entire yard and garden. Use a fan spray setting to provide great uniform coverage. Make sure the reservoir is filled to the maximum. When the reservoir empties, no more product will be applied. Apply Reclaim IT in the late afternoon for best control since that is when Armyworms are most active. Depending on the severity of the infestation, it may be necessary to reapply the treatment until all damage to your garden has been undone or to completely eradicate Fall Armyworms. Watering or mowing your lawn during this period will negatively affect the results.
Safety and Precautions:
Whenever you handle pesticides, wear protective equipment in order to avoid contact with your skin or facial tissues that can cause irritation or discomfort.