Please raise your hand if you have been anticipating an email from Hall | Stewart this morning about armyworms.

WoW… everyone’s hand is up!

What a week!

About 10 days ago, I saw a couple of armyworms, and the same day a lawn care tech reported seeing a few. Since it is common to see a few armyworms this time of year, it didn’t create much concern. But, by Monday, the armyworm populations, particularly in NE Edmond were increasing and lawns were being damaged. Each day brought more concerns, more turf damage, and more areas of the metro reporting armyworms. By the end of the week, every lawn care tech at Hall | Stewart was focused on one thing…

ARMY WORM CONTROL!

The mature Army Worm is 1 1/2” long, green to brown in color, with stripes down each side.

What is an armyworm?

How many Army Worms can you see in this picture?  Their green to brown color makes them hard to spot. — How many Army Worms can you see in this picture? Their green to brown color makes them hard to spot.

The adult form of an armyworm is a dark gray moth with mottled wings with darker and lighter splotches and a 1 ½” wingspan. Because armyworms do not overwinter in our climate, the moths migrate from the Gulf Coast and Mexico each year arriving in our area in late June.
Each moth can lay over 1,000 eggs.
By early July, the first generation of eggs have hatched, and the caterpillars go on a feeding frenzy that lasts 2-3 weeks.
Early caterpillars are green and very small and don’t cause any damage until they reach 1”. Quickly they grow into a brown, almost black, 1 ½” long caterpillar with black and reddish-brown stripes on each side of the body and small black spots on the top. Their distinctive mark is an inverted “Y” on the front of the head.
At the end of the 2-3 week feeding period, the worm burrows 1” into the soil and enters the pupal stage. 7-10 days later they emerge from the soil as a moth and the life cycle starts all over.
The average entire life cycle lasts about 28 days. There can be 4 to 5 overlapping generations, from July through early November, or until we have our first hard freeze.
Armyworms are always present in our summer lawns and landscapes. When populations are normal, you may never know they are there. But, with the right conditions, we can see an explosion to turf damaging levels in a matter of days.

While standing in this area while Army Worms were actively feasting, I had the sensation that the lawn was moving moving.

Army Worms have completely destroyed a new fescue lawn.

What is the typical host plant?

The armyworm feeds on a wide variety of plants. They prefer any leafy, soft plant with plenty of moisture in the leaf. They love alfalfa and Bermuda hay fields and all turf grass varieties.
The last time armyworms caused widespread damage in the area, they feasted on Bermuda and did little to no damage to fescue lawns. This time, they have preferred fescue over Bermuda. We have seen lawns where they have wiped out the fescue and skipped the Bermuda completely in favor of moving to another lawn with fescue. But as populations have increased, we are seeing more activity in Bermuda lawns.

If you have a healthy, growing, green turf of any variety, your lawn is currently considered a host location for armyworms.

Will armyworms kill a lawn?

Armyworms are primarily surface feeders. Small to moderate infestations will consume the leaf of the plant and the lawn will recover over time with sufficient moisture and fertilizer. In large numbers, the worms will consume the crown of the plant and are capable of killing a lawn.

How do you know if you have armyworms?

Check leaf blades in areas where the turf is browning. If your blades look like this one with jagged edges, you have Army Worms.

Because of how widespread and large the current population is, daily or at least every other day, inspection of the lawn is important. Early detection is the best control.
With the armyworm population as high as it currently is, you may only have to look at your sidewalks to see them marching to the next blade of grass.
Early signs of armyworm damage will appear as drought stress. Don’t dismiss areas that you think may just not be getting enough water.
Stand in the area that looks stressed. If the population is heavy enough, you will have the sensation that the grass is moving.
Still not sure? Get down on your knees and inspect the area. Because of their green to brown color, the worms can be hard to spot while standing.
Still don’t see any worms? Test the area with a soap flush. Mix 1 teaspoon of a lemon-scented dish soap in 1 gallon of water. Pour over the area. If you have armyworms, they will come to the surface. 2 to 3 worms per square foot, you need to treat.
Armyworms feed heaviest in the evening, night, and early morning. They often are hard to find in the middle of the day.

Why are armyworms a problem this year?

We have armyworms every year. With normal populations, they are not a problem. The problem is only when the populations are large.
One reason why the populations are so high this year is the cool, wet conditions we had in late June and early July. Armyworm eggs and worms have a higher survival rate when there is abundant moisture and cooler temperatures. This year, just as the moths arrived and laid eggs in late June, the weather turned cool and moist resulting in more worms
A second reason is the absence of natural predatory insects. Some wasp, flies, and beetles are natural enemies of the armyworm. Possibly the hard winter reduced the natural enemy populations.

This spot in a bermuda lawn appeared to be lack of water, but while inspecting the area I discovered army worms.

How do you control armyworms?

A quick response is important. Armyworms can wipe out a football-sized lawn in 2 days.

Inspect your lawn today!

If you see any signs of armyworms or turf damage,

call (405)367-3873 or respond to this email.

We will put you on the schedule for an insecticide application ASAP!

Treatment, when worms are small before they become heavy feeders, is best. The armyworm consumes 80% of their total consummation in the last two days of their worm stage.
Any insecticide labeled for caterpillar control in turf will be effective. One product to look for is Ortho Bug B Gon Insect Killer for Lawn.
When making any application remember the label is the law. Always read and follow all label instructions.
After treatment, keep up regular inspections. With a 4-week life cycle and overlapping generations, continue to be proactive in watching for increasing populations of armyworms.

This bermuda lawn had a similar browning area as the last lawn. But after not finding any worms, I checked the irrigation and discover a head that was not working and the discoloration was a watering issue.

Will your lawn recover?

If the worms only ate the leaves, the lawn will recover. If they destroyed the crown, there is a possibility the lawn will not recover.
If you have a Bermuda lawn, continue normal watering and fertilizing. There is still time for the lawn to return to a healthy condition before the end of the growing season.
For fescue lawns, recovery will be slower and will be delayed until we see cooler temperatures. This is already the most stressful time of the year for fescue. The best time to reseed fescue is September through October, only a few weeks away. If you have experienced armyworm damage on your fescue lawn, plan on overseeding this fall.

Need help with fall overseeding of your fescue?

Call (405)367-3873 or respond to this email for an estimate.

So, the trials and saga of the lawn and landscape continue in central Oklahoma.

I am still confident we will return to a more normal cycle soon. But, until then, we will continue to guide and assist you toward the best outdoor landscape possible.

Keep up the fight…it is worth it!

Lorne Hall

Hall | Stewart Lawn + Landscape

(405)367-3873