Choristonera Lederer
Type species: diversana Hübner
DIAGNOSIS
External characters:
Venation:
venation C. diversana
Forewing: All veins are separate.
Hindwing: M 3-CuA 1 extending from one point or strongly approaching basally.
Forewing shape and markings:
examples of Choristoneura
Species of the genus Choristoneura have relatively large forewings; apex especially in females often somewhat produced. Costal fold present or absent. Ground colour of forewing yellowish to brownish; markings consisting of a basal blotch, a median fascia and a subapical spot.
Sexual dimorphism:
Males often smaller than females; apex of forewing often more produced in females. Markings can be less well-odefined in females.
Genitalia:
Male:
male genitalia C. diversana ; male genitalia C. lafauryana
Uncus species specific, often club-shaped, in several species broad, rather short, with weak brush of hairs ventrally. Dorsal surface of uncus distinctly elevated above surface of its basal lobes; gnathos arm simple; socius variable. Valva distinctly tapering posteriorly or almost uniformly broad beyond middle; valva with better differentiated dorso-proximal portion provided with bunch of long scent scales. Sacculus simple or provided with 1 or 2 thorns or processes; its free termination often strongly reduced. Transtilla band shape, somewhat expanding dorsally or laterally; juxta simple; lobes of anellus often large. Aedeagus with caulis short or strongly elongate; coecum penis small; cornuti numerous long spines.
Female:
female gen. C. diversana ; female gen. C. lafauryana
Anterior portion of sterigma short or almost completely atrophied, rarely cup-shaped; postvaginal part in some species tapering beyond ostium anteriorly, then expanding into distinct lateral arms. Ductus bursae very long, with long cestum.
Early stages:
Eggs are often greenish in colour and are deposited in large batches.
Swatschek, 1958, provides the following diagnosis for the larvae, based on chaetotaxy of 2 Palaearctic species. SV group on first, second and seventh abdominal segment trisetose, bisetose on eighth and ninth abdominal segments. Seta V1 is clearly distanced from coxa on metathorax. Spiracle on abdominal segment 2-7 clearly bigger than basal ring of seta SD1. Spiracle of prothorax and eight abdominal segment round, the other spiracles elliptical. The V setae are not set further apart on the ninth segment than on the eighth segment. Second stemma equidistant from first and third. Crochets completely biordinal.
Biology:
The number of generations per year varies. Hibernation occurs in the egg or larval stage. Larvae are often polyphagous.
Distribution:
The genus occurs in the Palaearctic and Nearctic Regions.