Gypsonoma haimbachiana

Status

NATIVE

DOMESTIC SURVEY

Taxonomy

Gypsonoma haimbachiana (Kearfott) (Tortricidae: Olethreutinae: Eucosmini)

Common name: cottonwood twig borer moth

Adult Recognition

FWL: 5.5–7.5 mm

Head, thorax pale to dark gray; basal third of forewing concolorous with thorax, sometimes with a darker patch along inner margin; distal two-thirds of forewing pale gray to white, occasionally suffused with tan scaling; ocellus variously defined, typically faint; a black semi-circle present at apex; male without costal fold; hindwing brown to gray.

Male genitalia characterized by an obsolete uncus; socii large; valvae large, broad. Female genitalia characterized by a ring-like sterigma; some sclerotization of the ductus bursae; and two tack-like signa in the ductus 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 approximately 7 mm in length; width of head 0.9–1.1 mm; head yellowish brown; prothoracic shield brown or yellowish brown with brown lateral pigmentation; legs and anal shield brown; body, pinacula yellowish; anal fork absent; SV group on A1, 2, 7, 8, 9 typically 2:2:2:2:1.

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..

Similar Species

Gypsonoma haimbachiana could be confused with other species of Gypsonoma such as G. salicicolana, which is a smaller willow-feeding species, FWL: 4.5–5.5 mm, and has a more brown forewing in addition to differences in the genitalia. Adults of G. haimbachiana are also remarkably similar in forewing pattern to Rhopobota finitimana, a smaller holly-feeding species. The genitalia of both sexes are quite distinct.

Distribution

Gypsonoma bolliana is broadly distributed in eastern North America, from Maine, southern Ontario, and Minnesota south to Florida and Texas. There are a few records from Colorado which require verification.

Biology

The following account is summarized from Morris (1967)Morris (1967):
Morris, R.C. 1967. Biology of Gypsonoma haimbachiana (Lepidoptera: Olethreutidae), a twig borer in eastern cottonwood. Annals of the Entomological Society of America. 60: 423-427..

In the Mississippi Delta, eggs are laid on the upper surface of the leaves of the host plant, usually along the midrib. Eggs hatch in approximately five days at which point the young larva spins a small silken shelter and tunnels into the midrib or a major vein of the leaf. The larva molts into the second instar approximately three days later, abandons this first shelter and tunnels into a tender twig tip. The larva feeds in one or two twig tips for approximately three weeks and emerges as a fifth instar larva to move down the tree onto bark or to the ground to pupate. The adult moth emerges approximately eight or nine days later. Adults only live for five to ten days. A complete life cycle is completed in approximately 40–45 days. There are several generations per year. Overwintering occurs as a second star instar in a bark crevice or hollowed out bud. Adults can be found from approximately May to September in most areas, but the flight window is longer in Florida and Texas, approximately April to October.

The primary host is eastern cottonwood (Populus deltoides), but larvae have been less commonly reared from other species of Populus.

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.