Fall Armyworms Invading Causing Problems

Jack L. Baldwin, Coolman, Denise, Stephens, Matthew F.  |  4/19/2005 10:29:16 PM

Armyworms are invading fields, pastures and lawns in Louisiana. Populations can build very quickly and can devastate the grass on a field overnight, according to experts with the LSU AgCenter.

News Release Distributed 08/16/04 

Fall armyworms are invading the state, and LSU AgCenter specialists say they expect the worms to hang around until cool weather comes in.

"I think they’re worse this year than they have been in the past few years," said Dr. Jack Baldwin, an LSU AgCenter entomologist. "It’s a statewide problem, and I expect them to be a problem until the first frost comes in."

Armyworms are pests that invade fields, pastures and lawns. Populations can build very quickly and can devastate the grass on a field over night.

The pests can reoccur about every 30 days, so their numbers can rise and descend throughout the summer and fall. But Baldwin said he isn’t sure why the population is so heavy this year.

"There is no one thing to point to," the entomologist said. "It seems like the last epidemic was during a dry year – and this year hasn’t really been all that dry."

Matthew Stephens, an LSU AgCenter area agent in Northeast Louisiana, said the worms have been destroying hay fields.

"One hay field was ready to be cut when the worms came in," Stephens said. "One day it was a beautiful field, and the next day there was nothing to it. This field was expected to produce 1.5 tons per acre, and, at $60 a ton, that’s a lot of money gone."

The worms can be spotted early in the morning or late evening, Stephens said. High bird populations feeding early in the morning or late in the evening on fields are indications of a population of armyworms, the experts said.

"If I see an excessive number of cattle egrets or crows in a field, I take a close look at the grass in that field," Stephens said.

Baldwin said the best way to detect armyworms is to "just look for them." He said to use a sweep net or give the forage a visual inspection.

How much damage is done depends on what stage the worms are in when they attack a field or lawn.

"When the worms are in their early stages, they are real small and don’t consume a lot of foliage," Baldwin said. "But when they get large, they can consume a whole lot (of foliage) in a short time and, thus, do a lot of damage."

Baldwin said sprays with Sevin, Confirm, Lannate, or Methyl Parathion will stop the armyworms quickly.

For more information on controlling insect pests in your lawn or field, contact the LSU AgCenter office in your parish or visit to www.lsuagcenter.com.


Jack Baldwin at (225) 578-2369 or jbaldwin@agcenter.lsu.edu
Matthew Stephens at (318) 644-5865 or mstephens@agcenter.lsu.edu
A. Denise Coolman at (318) 644-5865 or dcoolman@agcenter.lsu.edu

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