Gretchena bolliana

Status

NATIVE

DOMESTIC SURVEY

Taxonomy

Gretchena bolliana (Slingerland) (Tortricidae: Olethreutinae: Eucosmini)

Common name: pecan bud moth

Adult Recognition

FWL: 7.0–9.0 mm

Head, thorax gray, sometimes faintly tinged with green; forewing with ground color gray, similarly tinged in some individuals; black streak present at end of discal cell, sometimes continuous with black streaks on costal side of ocellus and basal half of forewing to form a single streak from base to apex; ocellus poorly-defined; male without costal fold; hindwing gray-brown.

Male genitalia are characterized by a small uncus, socii, and a uniquely-shaped cucullus. Female genitalia are characterized by an ostium shielded by the posterior portion of sternum VII and two thorn-like signa in the corpus bursae.

Larval Morphology

The following account is summarized from MacKay (1959)MacKay (1959):
MacKay, M. R. 1959. Larvae of the North American Olethreutidae (Lepidoptera). Canadian Entomologist, Supplement 10: 1-338..

Mature larva 12–14 mm in length; width of head 1.3–1.6 mm; head yellow, dark brown in some specimens, with black pigmentation laterally; thoracic shield yellow to dark brown; body, legs pale yellow-green; anal fork moderately to well developed; SV group on A1, 2, 7, 8, 9 typically 3:3:2:2:2.

Detailed figures of larval chaetotaxy are available in MacKay (1959)MacKay (1959):
MacKay, M. R. 1959. Larvae of the North American Olethreutidae (Lepidoptera). Canadian Entomologist, Supplement 10: 1-338..

Pupa approximately 7–8 mm in length, caramel brown.

Similar Species

Gretchena bolliana is very similar to several other species of Gretchena, especially G. deludana. Gretchena deludana tends to fly earlier in the year than G. bolliana and has narrower black streaks on the forewing. Examination of the genitalia may be necessary to positively identify G. bolliana. The shape of the cucullus in males and shape of the posterior portion of sternum VII are diagnostic characters for species of Gretchena.

Distribution

Gretchena bolliana is broadly distributed in the eastern United States, from New Jersey to Minnesota, south to Florida and eastern Texas. Much of the range of this species is outside of the natural range of pecan (Carya illinoisensis); its range expansion has likely been facilitated by the widespread planting of pecan for both agricultural and ornamental purposes. It could also preferentially use other hosts such as hickory (Carya spp.) and walnut (Juglans spp.) in these areas.

Biology

The following account is summarized from Moznette et al. (1931)Moznette et al. (1931):
Moznette, G. F., Bissell, T. L., Adair, H. S. 1931. Insects of the pecan and how to combat them. United States Department of Agriculture, Farm Bulletin. 1654: 1-59..

Eggs are laid on branches near buds of the host plant in the early spring. Later in the year the next generations of adults lay eggs on leaves themselves. Larval development takes approximately 25 days. Pupation occurs in rolled leaves or infested buds with adult eclosing one to two weeks later. There are several generations per year (up to six in Florida). Adults can be found year-round in Texas, Louisiana, and Florida. Further north, overwintering occurs in the adult stage; females will lay eggs as soon as buds begin to open in the spring.

The preferred host is pecan (Carya illinoisensis), which larvae can be a significant pest of in nurseries and young orchards. Adults have also been reared from walnut (Juglans spp.) and hickory (Carya spp.).

Plant Associations

View full screen host table here

Links

Additional photos and a distribution map of this species in North America are available at Moth Photographers Group.