Oklahoma State University Turfgrass Science |
Fall Armyworms
Life Cycle
Fall armyworm does not overwinter in Oklahoma. It reinfests the state each year by moths that migrate northward from the Gulf Coast, Texas, or Mexico. Migrating populations usually reach Arkansas and Oklahoma by late June. Each female lays about 1,000 eggs in masses of fifty to several hundred. Larvae are present by early July. After feeding for two to three weeks, larvae dig into the soil to pupate. A new generation of moths emerges about two weeks later. There are several overlapping generations extending into October or even November in some years.
Hosts
This species will feed on a very wide variety of plants but prefers grasses. Most turfgrasses are subject to infestation.
Damage
Fall armyworms are potential turf pests in
late summer and fall. Large numbers can
consume all above-ground plant parts, and they are capable of killing or
severely retarding the growth of grasses.
This species may migrate in large numbers in search of new areas in
which to feed. Moths are attracted to
lights and may lay masses of eggs on non-host plants, walls, clothes on lines,
etc.
Inspection and Control
An infestation in turf can be detected by applying irritants such as dish detergent. Add one-quarter cup of dry or one ounce of liquid detergent to one gallon of water in a sprinkling can and apply the solution to one square yard of turfgrass where an infestation is suspected. Also effective is mixing one tablespoon of a commercial garden insecticide containing 1 percent to 2 percent pyrethrin in one gallon of water. If the thatch is dry, irrigation before the test is advisable. The caterpillars will surface within 10 minutes of soaking and can be found by separating the blades of grass. Treatment may be needed when 5 to 10 larvae are found per square yard of turf.