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CAPS Non-target - Adult

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

Common names: eastern blackheaded budworm

Synonyms: angusana (Peronea)

Fig. 1: Adult

Fig. 1: Adult

Fig. 2: Adult

Fig. 2: Adult

Fig. 3: Adult

Fig. 3: Adult

Fig. 4: Forewing patterns

Fig. 4: Forewing patterns

Fig. 5: Male genitalia

Fig. 5: Male genitalia

Fig. 6: Female genitalia

Fig. 6: Female genitalia

Fig. 7: Early instar larva

Fig. 7: Early instar larva

Fig. 8: Late instar larva

Fig. 8: Late instar larva

Adult Recognition

FWL: 7.5-9.5 mm

The forewing pattern of A. variana is quite variable and many forms are shared with Acleris gloverana. Powell (1962) describes eight different forms for A. gloverana and an additional form for A. variana. The most common forms are illustrated here. Males lack a forewing costal fold.

Acleris variana is nearly identical to Acleris gloverana in both biology and morphology. The two species are geographically separated: A. gloverana 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. gloverana, while it is narrower and more elongate in A. variana. In A. gloverana 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. gloverana females.

Larval Morphology

Larvae are approximately 11-15 mm in length and are bright green with a black head. The black head is lost in the final instar, where both the head and prothoracic shield are brown. An anal comb is present with 6-10 teeth.

Biology

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 Acleris gloverana.

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 intars 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 4 larval instars while the remaining females complete 5 instars. Pupation occurs in webbed needles. Adults eclose in approximately two weeks.

Larval damage is similar to that of Acleris gloverana, although outbreaks of A. variana do not tend to cause tree mortality. Periods of low rainfall tend to trigger increases in A. variana populations.

Host plants

Acleris variana attacks primarily fir and spruce. It has been recorded from the following hosts:

Family Genus/species Common name
Cupressaceae Thuja plicata Donn ex D. Don western redcedar
Pinaceae Abies alba Mill. silver fir
Pinaceae Abies amabilis (Douglas ex Louden) Douglas ex Forbes Pacific silver fir
Pinaceae Abies balsamea (L.) Mill. balsam fir
Pinaceae Abies grandis (Douglas ex D. Don) Lindl. grand fir
Pinaceae Abies lasiocarpa (Hook.) Nutt. subalpine fir
Pinaceae Abies Mill. fir
Pinaceae Larix Mill. larch
Pinaceae Larix occidentalis Nutt. western larch
Pinaceae Picea A. Dietr. spruce
Pinaceae Picea abies (L.) Karst. Norway spruce
Pinaceae Picea engelmannii Parry ex Engelm. Engelmann spruce
Pinaceae Picea glauca (Moench) Voss white spruce
Pinaceae Picea mariana (Mill.) Britton, Sterns & Poggenb. black spruce
Pinaceae Picea pungens Engelm. blue spruce
Pinaceae Picea rubens Sarg. red spruce
Pinaceae Picea sitchensis (Bong.) Carriere Sitka spruce
Pinaceae Pinus contorta Douglas ex Loudon lodgepole pine
Pinaceae Pseudostuga Carriere Douglas-fir
Pinaceae Pseudotsuga menziesii (Mirb.) Franco Douglas-fir
Pinaceae Tsuga canadensis (L.) Carriere eastern hemlock
Pinaceae Tsuga heterophylla (Raf.) Sarg. western hemlock
Pinaceae Tsuga mertensiana (Bong.) Carriere mountain hemlock
Salicaceae Populus balsamifera L. balsam poplar

Distribution

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

References

EPPO (European and Mediterranean Plant Protection Organization). 1997. Data sheets on quarantine pests: Acleris variana and Acleris gloverana . http://www.eppo.org/QUARANTINE/insects/Acleris_gloverana/ACLRSP_ds.pdf [accessed 7 Mar 2011].

Otvos, I. S. 1991. North American species in forestry, pp. 719-756. In L. P. S. van der Geest and H. H. Evenhius [eds.], Tortricid Pests: Their Biology, Natural Enemies, and Control. World Crop Pests, Vol. 5. Elsevier, Amsterdam.

Powell, J. A. 1962. Taxonomic studies on the Acleris gloverana -variana complex, the black-headed budworms (Lepidoptera: Tortricidae). Canadian Entomologist. 94: 833-840.

Powell, J. A. and P. A. Opler. 2009. Moths of western North America. University of California Press, Berkeley. 369 pp.

Photo Credits

Fig. 7: Rick West, Canadian Forest Service, Bugwood.org

Fig. 8: Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org

Tortricids of Agricultural Importance by Todd M. Gilligan and Marc E. Epstein
Interactive Keys developed in Lucid 3.5. Last updated August 2014.