Other Common Names
Defoliating Moth (Agriculture Canada)
Synonyms and other taxonomic changes
Aplocera plagiata (Linnaeus, 1758)
formerly Anaitis plagiata
Explanation of Names
PLAGIATA: from the Greek "plagios" (oblique); possibly refering to the lines on the forewing
the only species in this genus in North America.
Adult: forewing brown to gray with triple AM, median, and PM lines containing faint cross-bars, giving the appearance of sheet music (perhaps the origin of the common name, Treble-bar); dark apical dash with yellowish or orangish shading
hindwing pale grayish with tiny black discal spot.
at rest, wings are held together but not overlapping, giving an overall triangular shape
Larva: head small, brown; body stout, gray dorsally with broad white lateral stripe, brown ventrolaterally, and pale brown below.
Native to Europe; introduced to British Columbia in 1976, and the Ottawa area of Ontario in the 1980s to control St. Johnswort. It has since spread to Quebec.
First recorded in United States in 2003 (near Plattsburgh, New York)
Moth Photographers Group
- large map with some collection locations and dates.
dry fields and waste places containing St. Johnswort
adults fly during May and June, and again in August and September (two broods)
larvae feed on leaves of St. Johnswort (Hypericum spp.)
two generations per year; up to 300 white eggs are laid singly or in groups on flowers and leaves of host plant; overwinters as a larva in the soil; pupates in May (first brood) and again in August
Introduced to North America in an attempt to control St. Johnswort, which is considered a weed in many areas; attempts to establish the moth in the maritime provinces have been unsuccessful.
Larvae can feed in sunlight, as their cuticle filters out 80 percent of the sun's ultraviolet rays.