Acleris variana

Status

NATIVE

DOMESTIC SURVEY

Taxonomy

Acleris variana (Fernald) (Tortricidae: Tortricinae: Tortricini)

Common names: eastern blackheaded budworm

Synonyms: angusana (Peronea)

Adult Recognition

FWL: 7.5–9.5 mm

The forewing pattern of Acleris variana is quite variable and many forms are shared with A. gloveranus. Powell (1962b)Powell (1962b):
Powell, J.A. 1962b. Biological and taxonomic notes on two California species of Proteoteras (Lepidoptera: Tortricidae). Pan-Pacific Entomologist 38: 191- 195. describes eight different forms for A. gloveranus and an additional form for A. variana. The most common forms are illustrated here. Males lack a forewing costal fold.

Male genitalia are characterized by a well-developed uncus; moderately developed, lobe-like socii; and elongate valvae with a well-developed sacculus. Female genitalia are characterized by sterigma with long anterolateral extensions; cestum present in the ductus bursae; and elongate, scobinate signum present in the corpus bursae.

Larval Morphology

The following account is summarized from MacKay (1962a)MacKay (1962a):
MacKay, M. R. 1962a. Larvae of the North American Tortricinae (Lepidoptera: Tortricidae). Canadian Entomologist, Supplement 28: 1-182..

Mature larva 14–16 mm in length; width of head 1.3 mm on average; head variable in color, brownish yellow, reddish brown, light brown, or black; prothoracic shield yellow or green, bordered laterally and posteriorly with brown or black, occasionally entirely brown; legs brown; body bright green; an anal comb present with 6–10 teeth; SV group on A1, 2, 7, 8, 9 typically 3:3:2:2:2.

Similar Species

Acleris variana is nearly identical to A. gloveranus in both biology and morphology. The two species are geographically separated: A. gloveranus occurs in western North America and A. variana occurs in eastern North America. Powell (1962) outlined minor genitalic differences that can be used to separate the two species. In males, the sacculus is broader and less elongate in A. gloveranus, while it is narrower and more elongate in A. variana. In A. gloveranus females, the sterigma is broad, with lobes connected, and a cestum is absent. In A. variana females, the sterigma is narrow with the lobes separate, and a weakly sclerotized cestum is present. In addition, females of A. variana have large abdominal scale tufts that are used to cover the eggs; these are lacking in A. gloveranus females.

Distribution

Acleris variana is distributed in coniferous forests from eastern Canada and the northeastern United States west to Alberta.

Biology

The following account is summarized from EPPO (1997)EPPO (1997):
EPPO (European and Mediterranean Plant Protection Organization). 1997. Data sheets on quarantine pests: Acleris variana and Acleris gloverana . https://gd.eppo.int/download/doc/797_ds_ACLRSP_en.pdf [accessed 15 October 2020] (.pdf)..

Acleris variana completes one generation per year. Adults are present in August and September. The A. variana life cycle is nearly identical to that of A. gloveranus. Females lay eggs on the underside of needles in the upper section of host trees. Eggs overwinter until the following spring, and larvae hatch starting in mid May. First instars feed inside opening buds, mid-instars web together needles to create a nest, and last instars are free-feeding. Males and 50% of females complete four larval instars while the remaining females complete five instars. Pupation occurs in webbed needles. Adults eclose in approximately two weeks. Larval damage is similar to that of A. gloveranus, although outbreaks of A. variana do not tend to cause tree mortality. Periods of low rainfall tend to trigger increases in A. variana populations.

Acleris variana attacks primarily fir (Abies spp.) and spruce (Picea spp.). It has been recorded from the following hosts.

Plant Associations

View full screen host table here

Links

Additional photos and distribution map in North America available at Moth Photographers Group.