Other Common Names
Potato Stem Borer (larva)
Size
wingspan 28-45 mm (UK Moths); 32-40 mm (Charles Covell)
larvae to 40 mm
Identification
Adult: forewing light to medium brown with dark brown shading in lower median area; PM line very slightly arced (almost straight) except for sharp inward bend near costa; AM line composed of 2 arcs: small one at costa, and much larger one crossing 2 veins and extending to inner margin; ST line wavy, often indistinct, with darker shading beyong it; terminal line slightly wavy
hindwing pale shiny brown with gray veins, median line, and arced discal spot
Larva: body pinkish or pale purple with dark band across each abdominal segment
Range
Newfoundland to Massachusetts, west to Ontario and Wisconsin; spreading southward and westward
Habitat
fields, waste places, grassy or weedy borders of corn fields
Season
adults fly from late July to September
Food
larvae bore in stems of dock (Rumex spp.), burdock (Arctium spp.), plantain, potato, tomato, grasses, and many other low plants; can be a pest in corn fields
Life Cycle
one generation per year; overwinters as an egg which hatches in May; young larvae bore in stems of grass and weed seedlings, then migrate to larger plants such as corn as they mature; pupation occurs in surface soil in July; adults emerge in late July or early August; in September, 50-75 eggs are laid in parallel rows on leaf sheaths of grass, especially Quack Grass
Remarks
A European species introduced to maritime Canada in the early 1900s
See Also
Hydraecia perobliqua forewing lacks dark brown shading in lower median area, has a straight PM line with beveled angle near costa, and AM line composed of 3 fairly equal arcs.
H. immanis (Hop Vine Borer) is larger (wingspan to 55 mm), forewing more pinkish-brown and lacks dark brown shading in lower median area, PM line bent above middle, and AM, PM, ST lines double
Nephelodes minians and Lacinipolia lorea are also superficially similar.
Internet References
live adult images plus food plants and common name reference [Rosy Rustic; adult] (Ian Kimber, UK Moths)
live adult images (Moths and Butterflies of Europe & North Africa)
live adult image (Hants Moths, UK)
live adult image (Josef Hlasek, Czech Republic)
food plants plus links to live and pinned adult images (Markku Savela, FUNET)
distribution plus biology, damage, control methods, common name reference [Potato Stem Borer; larva] (Agriculture Canada)
food plants plus biology, control methods (U. of Vermont)
