Instar requires about 7 days to complete development, depending on Non-parasitized larvae (¾ to 1 ¼ inches long) per linear foot or rowīefore extensive head cutting occurs. In small grains, treat for armyworms when there are 6 or more After pollen shed, insecticide control may be justified In seedling corn, control may be justified when 25% of the plants areīeing damaged. If armyworms move intoįields and infest crop areas, and insecticide treatment may be Watch for movement of armywormsįrom grass or weedy areas to field borders. Not only will moth egg laying activity be reduced, but so will The risk of potential armyworm infestations can be minimized byĬontrol or elimination of grassy weeds in from fields or field borders. A cool and wet spring favors armywormĭevelopment while hindering parasite and predator populations. There are several types of viruses, a microsporidium, and fungi that
On the other hand, Meteorus communus lays only one egg per host (solitary parasitoid) and attacks second to fourth instar armyworms. Parasitoid since many larvae develop in one host. The parasitoid, Glyphanteles militaris inserts as many as 60 eggs at a time and is known as a gregarious Cotesia marginiventris, a braconidwasp is one of the most common. Near the head so the armyworm can bite them off. Tachinid flies, such as Nemosturimia rufopicta, lay eggs on Photo courtesy of Matt Montgomery, UI Extension Larvae will feed on the flag leaves, kernels, and clip the Strip the leaf margins and move up the plant to feed on the panicles orįlowers. Ordinarily armyworms that attack young corn migrate from smallĪrmyworm larvae chew the leaves of small grains and grasses. Corn generally recovers from damageĬaused by moderate infestations if the growing pointhas not been Feeding is usuallyĬonfined to leaf margins, but in some instances, larvae may strip the This usually occurs duringĪrmyworms consume leaf tissue of corn plants. Host plants such as small grains and corn.
As larvae run out of available food sources, they move to other Used to control the weeds, larvae move from the dead grasses to theĬorn. Consequently, theseįields armyworms are often a problem in these fields. Oviposition sites often include weedsĪnd grassy in weedy or reduced tillage fields. Infestations generally develop in areas such as grass pastures, Since moths prefer dense vegetation for oviposition sites, armyworm
Photos courtesy of Matt Montgomery, UI Extension Armyworm injury in popcorn field planted in rye
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