Decodes basiplagana (Walsingham) (Tortricidae: Tortricinae: Cnephasiini)
FWL: 8.0–9.0 mm
Forewings are gray with a strongly arched costa. Forewing pattern varies greatly, with some individuals expressing well-defined dark-gray and black fasciate markings, and others being unmarked. Males lack a forewing costal fold.
Male genitalia are characterized by a long, slender, minutely spined uncus; setose socii; and elongate, narrow valvae. Female genitalia are characterized by unusual, modified papillae anales; and a signum present in the corpus bursae as a elongate patch of spine-like scobinations.
Larvae have not been described.
Decodes fragariana is similar, but males have an aedeagus that is curved more than 90 degrees, and females lack a signum in the corpus bursae. Decodes montanus is similar to both species, but the male aedeagus is more strongly curved than in D. fragariana, and females of D. montanus have a band of dark scales on the seventh sternite that is lacking in the other two species. Wing pattern is not diagnostic and cannot be used to reliably separate the Decodes species included on this site.
Cnephasia stephensiana and other species of Cnephasia can appear superficially similar. The valvae of D. basiplagana are much more slender than in C. stephensiana and do not have such a well-sclerotized sacculus. Females of D. basiplagana have a significantly smaller signum than in C. stephensiana.
Decodes basiplagana is recorded from the eastern United States and ranges west into central Texas, Colorado, Utah, Arizona, and central California.
The life history of D. basiplagana is unknown, although it is assumed to be similar to that of D. fragariana.
Larvae have been recorded feeding on oak (Quercus spp.).
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Authors: KA Austin, TM Gilligan, ME Epstein
Content last updated May 2025
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