If you are in the forage business, whether it is the hay business or forage to feed beef or dairy cattle, horses, sheep or goats, then you need to be on the watch for armyworms. I have had several calls of confirmed cases of armyworms this week, and with the recent rain and cooler temperatures, you had better prepare for battle.
The armyworm has four life stages: egg, larva, pupa and adult. The adult is a moth that migrates northward as temperatures increase in the spring. The adult moth has a wingspan of about 1.5 inches. The hind wings are white; the front wings are dark gray and mottled with lighter and darker splotches. Each forewing has a noticeable whitish spot near the extreme tip.
Eggs are very small, white, and are laid in clusters of 50 or more, covered with grayish, fuzzy scales from the body of the female moth. The eggs are seldom seen and are laid at the base of appropriate host plants.
Larvae hatch from the eggs and when fullcrown, larvae are green, brown, or black and about 1 to 1.5 inches long when full grown. The larva has a dark head capsule, usually marked with a pale, but distinct, inverted “Y.” Along each side of its body is a longitudinal, black stripe, and along the middle of its back is a wider, yellowish-gray stripe with four black dots on each segment. The larvae have five stages, or instars, and usually hide in debris on the soil surface in the middle of the day. When full grown, larvae will enter the soil and form the pupa stage. Adult moths emerge from pupae. Moths mate and lay eggs, thus starting the life cycle over again. Lush plant growth is preferred by the adults for egg laying.