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Insects Associated with Maine Cranberries - False Armyworm

Order: Lepidoptera || Family: Noctuidae
Scientific Name: Xylena nupera (Lintner)

Photo of a mid-size false armyworm larva crawling on the edge of a US dime (shown for scale purposes) Photo showing several False Armyworm caterpillars together, next to (and some of them 'on') a cranberry upright for scale purposes Photo of a mature false armyworm caterpillar, munching on a cranberry upright Photo of two false armyworm caterpillars next to a US dime for scale purposes Photo of a false armyworm caterpillar attached to a cranberry upright and feeding on one of its leaves False Armyworm caterpillar feeding on a cranberry upright (mature/full-sized) (Photographed June 24th - Maine) Photo showing a mid-sized false armyworm larva next to a US penny for scale purposes

Description: 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 can be hard to identify when they are very young. Until they get bigger, they highly resemble spanworms because they will ‘loop’ somewhat while crawling the way that loopers (or spanworms) do. Unlike spanworms, however, false armyworms have three pairs of hind legs versus just 1 pair, and older larvae will have four pairs (you can see the legs clearly in the right-most photo above). Older, larger larvae–which can grow to two inches in length–will also have an obvious stripe running the length of each side of the body (the yellow portion of the striping is what tends to stand out the most, visually). Finally, false armyworms are usually some shade of green in color, especially lime green, but there is considerable variation in coloring (various shades of green, to dark brown, to black). False armyworm is univoltine, meaning it goes through just a single generation per year. It overwinters as a moth, and the females will lay about 600 eggs total, in masses of sometimes 100 or more, in late April and very early May. They are deposited on the cranberry stems or on the undersides of the leaves, and hatching of the eggs for much of Maine takes place, on average, starting generally (most years) in late May.

Sweepnet-Captured First Dates (Average First Date = May 23rd): 6/6/97, 5/28/98, 5/28/99*, 5/24/00, 5/31/01, 5/13/02*, 5/24/05, 5/25/07, 5/14/08, 5/14/09, 5/16/2013*♦, 5/20/2014*♦

Dates are when active insects were found for the first time during each indicated year on any commercial Maine cranberry bed.

* = 1st day scouting that year
♦ = central Maine; larvae were newly-hatched

Control: For specific and current control recommendations for Maine, please refer to the Maine Cranberry Pest Management Guide. Don’t forget that a Late-Water (LW) flood controls false armyworm very well.

Cranberry questions? Contact Charles Armstrong, Cranberry Professional. University of Maine Cooperative Extension || Pest Management Unit || 17 Godfrey Drive || Orono, ME 04473-3692 || Tel: 207.581.2967 [email:]


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