Insects & Other Pests ›
The fall armyworm is a sporadic but serious pest of turfgrasses in North Carolina. The larva is the damaging stage of this pest and it is 1 inch to 1½ inches long when fully grown. It can vary in color from green to brown, to almost black. There are four black dots on the dorsal side of each abdominal segment. It has a distinct inverted “Y” on the head. The true armyworm is similar in appearance but lacks the inverted “Y.” The moth has a wingspan of about 1 to 1½ inches. The hind wings are white; the front wings are dark gray, mottled with lighter and darker splotches. Each forewing has a noticeable whitish spot near the extreme tip. The eggs are very small and laid in clusters of 50-250. Egg clusters are fuzzy patches covered with scales from the female moth and resemble cotton. The mass is greenish white but turns darker prior to hatching. The pupa, approximately 1.2 inches long, is somewhat football shaped. It is reddish-brown at first, and darkens to black as it matures.
The fall armyworm is more difficult to control chemically than the true armyworm. Control of fall armyworms will be improved if you cut the turf prior to treating. A light irrigation prior to treatment may also help as will treating late in the day. Chemical control is needed if natural enemies do not keep infestations below the economic threshold of 1 per square foot on general turf or 1 per square yard on golf greens. If possible, do not mow turf and remove clippings for several days after treating for any of the caterpillar pests.
Large fall armyworms are difficult to control. Don't expect 90% control. If the worms are very large (inch and a half long) then they will go into the soil very soon to pupate and control efforts may be ineffective. Timing is important and a repeat application may be necessary in some situations. For specific control information, consult the NC Cooperative Extension Service recommendations.