Author: (Hübner, 1817)
Species Overview:
Adult: 15-23 mm wingspan; forewings pale brown, weakly strigulated distally and with deeper brown markings. Females more extensively strigulated. Hindwing pale grey-brown.
Egg: flattened, green; deposited in large batches.
Larva: head and prothoracic plate dark brown or reddish brown; abdomen usually green or greyish green, but varying to grey or greyish white; pinacula yellow.
Pupa: reddish brown, slender.
Taxonomic Description:
Male:
Choristoneura diversana male
Choristoneura diversana male 2
External characters: 15-20 mm wingspan; forewing somewhat narrowed anteriorly, without costal fold. Ground colour light brown, weakly strigulated distally; markings deeper brown. Basal blotch often atrophied, reaching one-third of dorsum; outer margin of basal fascia oblique, slightly convex; inner margin of median fascia slightly irregular at middle; subapical blotch variably developed, often strongly reduced. Cilia almost concolorous with ground colour. Hindwing grey varying to brownish grey; cilia paler (Bradley et al., 1973).
male genitalia C. diversana
apex of sacculus C. diversana
apex aedeagus C. diversana
8th sternite in Choristoneura spp.
Genitalia: Tegumen narrowed posteriorly as viewed antero-dorsally; median length as long as basal width; lateral side slightly convex as viewed antero-dorsally. Uncus narrow, gently curved; widest part of subapical area 1.5- to 2.0-fold width at subbase; ventral area of apical third with fine and short unbranched setae. Socius well developed, almost as long as uncus, curved ventro-anteriorly; anterior margin distinctly notched at midlength; dorsal area from notch to apex with dense, long and upcurved setae. Gnathos smooth; straight length from base to apex shorter than that of socius. Transtilla spiculate, bulbous medially. Aedeagus gently curved, moderately sclerotized; left side of distal half sharply narrowed ventro-apically; opposite side slightly narrower than width at midlength; apical margins oblique, thickened and well sclerotized; ventral apical angle finely serrate; dorsal apical angle with dorsally or dorso-anteriorly directed conical spine; aedeagal surface with numerous fairly coarse spicules; cornuti lanceolate. Valva subtriangular, as long as basal width. Sacculus smooth; ventral margin gently sinuate; dorsal margin distinctly raised into sharp bladelike ridge; distal end expanded meso-posteriorly forming triangular plate with bluntly acute apex as viewed ventrally.
8th sternite with long median process (Dang, 1992).
Female:
Choristoneura diversana female
C. diversana female 2
External characters: 19-23 mm wingspan; similar to male but forewing usually more extensively strigulated with darker brown. In darker specimens, the markings become diffuse and obscure.
female gen. C. diversana
Genitalia: Lamella postvaginalis with large semicircular incision in middle. Antrum elongate, well sclerotized; ductus bursae very long, thin, with very long cestum, signum long.
Variation:
In the male, the forewing ground colour varies slightly in intensity but is more often lighter than darker, in light specimens the markings tend to be stronger and more pronounced and may have the outer margin of the basal fascia and inner margin of the median fascia weakly edged with orange-brown; rarely the median fascia is interrupted above the middle. Occasionally the ground colour is dark brown but the markings remain moderately distinct (Bradley et al., 1973).
Biology:
There is a single annual generation. Moths fly in July in the UK. They fly during the evening and at dusk over the tops of young trees and bushes, later coming to light. During the day the moth rests among the foliage, dropping to the ground when disturbed. Eggs are deposited in large batches and hatch in August and September. Young larvae may graze on maturing fruits before hibernating until spring. They become full-grown by the end of May. In June, they pupate in the larval habitation or in spun leaves.
Host plants:
Apple (Malus), pear (Pyrus), plum (Prunus), raspberry (Rubus), Acer mono, Achillea, Alnus hirsuta, Betula spp., Lonicera, Morus bombycis, Populus nigra, Quercus, Rhamnus, Salix sp., Syringa, Trifolium, Ulmus davisiana, Ulmus laciniata.
Damage:
Larvae defoliate, and can sometimes be of minor economic importance in apple, pear and plum orchards. Before hibernating, young larvae may graze on maturing fruits. Leaf damage caused in the spring is not important (Alford, 1984).
Distribution:
Northern and Central Europe to Asia Minor, Caucasus and Western Siberia, Amur Region, Southern Primore, Korea, Japan.
Pheromone:
Pheromone unknown.
Attractantia:
14Z 11OH (Ivanova et al., 1988)
Parasitoids
Macrocentrus linearis (Braconidae)