False Armyworm

CRANBERRIES

False Armyworm
Order: Lepidoptera || Family: Noctuidae
Xylena nupera (Lintner)

(False armyworm larvae; LEFT=mid-size, RIGHT=Full-size)
(Left specimen from Washington County, Maine - June 2, 1998)

The false armyworm is a member of the cutworm group and its appetite is voracious! The young caterpillars will feed on new terminal buds, often before any new growth has started, although they will eat the new growth as well. They are hard to identify, especially when they are very young. Until they get bigger, they highly resemble spanworms because they will "loop" somewhat while crawling the way loopers (or spanworms) do. But unlike spanworms, they have 3 pairs of hind legs versus just 2, and older larvae will have 4 pairs (see picture below). Older, larger larvae will also have (typically) a white line running the length of each side of the body. Finally, false armyworms are usually some shade of green in color, especially lime green, but there is considerable variation in coloring. On the positive side, false armyworm is univoltine, meaning it goes through just a single generation per year.

The threshold for false armyworms is an average of 4.5 larvae per 25 sweeps.
*Be aggressive when sweeping or you may not capture any.

(False Armyworm larva, about 1/3 as large as when mature)
(Note the lateral white/yellow stripe and the 4 pairs of hind legs, excluding the pair at the very end of the larva)

If you have comments or questions about this page,
contact Charles Armstrong at: charlesa@umext.maine.edu

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These pages are currently being maintained by the Pest Management Office, University of Maine Cooperative Extension. Page Last Modified: 05/15/08