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Fig. 1: Typical citrana male

Fig. 2: Typical franciscana male

Fig. 3: Dark franciscana male

Fig. 4: Typical citrana female

Fig. 5: Male citrana syntype

Fig. 6: Resting adults and egg mass

Fig. 7: Late instar larva

Fig. 8: Late instar larva

Fig. 9: Larval prothoracic shield

Fig. 10: Male genitalia

Fig. 11: Male genitalia

Fig. 12: Female genitalia

Recognition

Diagnostic features

Adults

FWL: 5.6-9.9mm

In California this species has two common phenotypes: forewings orange-brown with a well defined dark median fascia and outer spot on the costa, hindwings white to gray; and forewings gray to brownish gray with a dark variably defined median fascia and an outer spot on the costa, hindwings primarily gray. Wing pattern and size can be quite variable although most individuals show remnants of a median fascia and outer costal spot. Males lack a forewing costal fold.

Larvae

The larval head and prothoracic shield are light brown and unmarked. Body color vaires with host plant, but larvae are usually pale to dark green.

Related or similar species

Choristoneura rosaceana males have been captured in franciscana pheremone traps; however, adults of these two species are unlikely to be confused.

Larval damage by Pandemis pyrusana may resemble that of franciscana and the larvae are similar in appearance. Argyrotaenia franciscana larvae can also appear similar to LBAM larvae.

Biology

Life history

This species is bivoltine or multivoltine, depending on location. In warmer inland areas of California, larvae aestivate during the summer and only two generations are completed. In cooler coastal areas there may be up to 5 continuous overlapping generations with adults present year-round.

Eggs are laid on smooth surfaces of leaves, fruits, and twigs in masses that contain approximately 200 individual eggs. Early instar larvae skeletonize leaves under a silk shelter; later instars roll, fold, or web leaves together or to fruits. Larvae complete 5-7 instars in a period of 20-30 days. Larvae or pupae overwinter in dead leaves, in mummified fruits, under buds, or on weedy herbaceous plants in the same vicinity as the host. Pupation occurs in the final larval shelter.

Larvae cause economic damage by directly feeding on developing fruit in citrus, apple, and grape. Larvae may also feed on stems, causing fruit to drop.

Host plants

Argyrotaenia franciscana has been described as one of the most polyphagous tortricid species in North America.  Its host list includes over 80 species of plants, many of economic importance. The following is a partial list: apple (Malus sp.), apricot (Prunus armeniaca), avocado (Persea americana), blackberry and raspberry (Rubus sp.), blueberry (Vaccinium sp.), grape (Vitis sp.), grapefruit (Citrus x paradisi), lemon (Citrus lemon), and Monterey pine (Pinus radiata).

Area of origin

California

Distribution

California north to Oregon and Washington; franciscana is found primarily in the cooler costal areas and river valleys

Taxonomy

Current valid name

Argyrotaenia franciscana (Walsingham)

Common names

  • orange tortrix
  • apple skinworm

Synonyms

Argyrotaenia franciscana and A. citrana were once considered separate species. Landry et al. (1999) concluded that they form a single species based on DNA evidence.

  • Argyrotaenia citrana, A. franciscana insulana, A. kearfotti
  • Eulia citrana, E. franciscana
  • Tortrix citrana

Placement

Tortricinae: Archipini

Selected References

Crop Protection Compendium. 2007 Edition. CAB International, Wallingford, UK, 2007.

Freeman, T. N. 1944. A review of the North American species of the genus Argyrotaenia Stephens. Sci. Agr. (Ottawa). 25: 81-94.

Landry, B., J. A. Powell and F. A. H. Sperling. 1999. Systematics of the Argyrotaenia franciscana (Lepidoptera: Tortricidae) species group: evidence from mitochondrial DNA. Annals of the Entomological Society of America. 92: 40-46.

 

Powell, J. A. 1964. Biological and taxonomic studies on tortricine moths, with reference to the species in California. University of California Publications in Entomology. Vol. 32. 317 pp.

Photo Credits

Figures 6-8 used with permission from University of California Statewide IPM Program. Please visit the 
UC IPM Web Site for more information.

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