Armyworms lead to run on pesticide, but beekeeper says think twice

A photo from Sara Nuzum of Hesston shows an armyworm and the brown it has left in its wake. The insects have been invading yards across the area this week.

By Adam Strunk

Armyworms have marched into Harvey County and yards across the area are falling beneath their onslaught.

Newton resident Clint McBroom noticed a few brown spots last week. Within four days, his green lawn had turned into a defoliated brownout. He said that at the height of the invasion, he counted 18 of the little greenish-black worms in a square foot. Multiplying that by the size of his yard would mean a force of more than 100,000 strong was chowing down on his grass.

“I did notice how much weeds I never thought I had,” he said. “They didn’t even touch those.”

Melissa Vajnar had a similar experience.

“At first when we discovered it, we thought that that section of the yard was just burning up from the heat,” she stated. “After closer inspection, we saw the armyworms and there were thousands of them. By the next day, that section of the yard was completely brown.”

What exactly are they?

According to KSU Research and Extension, the worms are tropical insects that overwinter in Florida and Southern Texas.

They’re moth larvae and as it warms up, the moths move north laying up to 1,000 eggs each. The eggs hatch and larvae then produce silken thread allowing them to be blown around. A generation can replicate and repeat every 23 days, but generally, they only can get between 2-4 generations in Kansas before it gets too cold for their life cycle.

Basically, they’re always around in Kansas during the summer. As to why they are worse, there doesn’t appear to be a definitive answer. Kansas isn’t alone in the outbreak as news stories from southern states weeks earlier indicate an abnormally large population.

What to do

The infestations in the area resulted in a run on pesticides throughout Newton.

Graber’s Hardware reported selling out of chemicals and when they restocked, a line formed out the door to buy the supplies, which sold out in about 30 minutes. Graber’s had a supply of smaller Sevin containers – a treatment recommended by the Extension office — Tuesday afternoon.

Orscheln Farm and Home also reported a demand on insecticides, stocking an additional cartload up at the front of the store only to have it sell within a day. Orscheln, as well as Tractor Supply, also had the smaller Sevin containers in stock.

Tractor Supply reported that the larger granulated bags of insecticide had sold out last Friday.

Along with Sevin, KSU Research and Extension recommended using cyhalothrin (Spectracide Triazicide), permethrin.

However, local beekeepers and conservationists asked people to think before immediately powdering or spraying their lawn.

The drawback with using intensive pesticides is the impact on helpful bug populations, such as bees and predatory insects that eat the eggs of the armyworm and younger larvae.

Gwen Neufeld of North Newton keeps bees and asked that those using insecticide be careful with them and follow directions as it can easily wipe out a hive.

“Every really effective treatment to kill the worms, of course is toxic to bees,” she said.

“I never thought it would hit in my back yard until last fall and I sat there watching one of my hives dying in front of me.”

She said the bees died with their tongues out and flailing, indicating poisoning.

She said if people followed directions on the products and were careful, they could keep bees safe.

“There are different ways to minimize bee damage.”

She said that if you do use pesticides, use them around dusk when the bees are not out. Also, don’t use them when rain or heavy dew is expected. If it’s a spray, give the spray a chance. She also said that applying the insecticide to well-maintained lawns isn’t harmful like it is to apply to flowers or lawns that have seeds or other flowers in them.

This is because the bees get sick when they’re taking nectar from the flowers. If the grass is short, there’s nothing for them to eat.

Dyck Arboretum in Hesston also cautioned residents about using pesticides on their lawn, but instead recommended an organic alternative.

“Use a biological control for caterpillars made from a naturally occurring soil bacteria. If you must spray, choose a biological control, if possible, to limit the effects on non-targeted species,” it stated in a social media post.

Will the worms kill your yard?

In short, probably not, according to the Extension Office.

“Tall armyworms seldom kill grass,” it stated. “Rather than nubbing a plant down to the crown and growing point, larvae will select a more tender adjacent grass blade to feed upon. Of course, under heavy feeding pressure, larvae may be forced to feed deeper down on a plant, but usually, when the food supply becomes scarce or ‘tough’, the larvae will move ‘in mass’ to adjacent areas where there is a ‘fresh stand’ of food to feed on.”

So, give the grass some time and it should green up again. Until then, you’re stuck living with the brown.

A before and after shot of Newton resident Clint McBroom’s yard in Newton shows what armyworms can do to a lawn in a matter of days.


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