|scientific name Gypsonoma haimbachiana |
common name Cottonwood Twig Borer
Occasional occurrence in small patches of grassland in boreal regions and forested patches in the grasslands (Pohl et al. 2010).
Adult flight periods occur in June to mid-August and specifically in June in Alberta (Gilligan et al. 2008, Pohl et al. 2010).
This genus has a forewing pattern that is uniform with the basal patch and median fascia well defined. This well defined region is also separated by an interfascial band of contrasting, lighter coloration. Male moths lack costal folds and notching near the base of their antennae. Male genitalia consist of a prominent clasper on the basal excavation margin and a cluster of long scales on the tegumen (near the area where the tegumen articulates with the vinculum). Female genitalia consist of two tacklike signa with some degree of sclerotization of the ductus bursae. The sculpturing of the sterigma is different between species (Heinrich 1923, Miller 1987, Gilligan et al. 2008).
This species has an alar expanse of 13-17mm (with their forewings 5.5-7.5mm in length) (Kearfott 1907, Heinrich 1923, Miller 1987, Morris 1967). The head is brownish-gray, with purplish-brown eyes. The palpi are grey and slightly darker apically. The antennae and thorax are also grey, with the anterior edge of the thorax spotted with brown, and a double brown dot behind the middle. The first three segments of the abdomen are tufted and pale, while the other segments are fuscous. Legs are whitish in coloration and banded with blackish-brown. The forewings are ashy-grey with lines, spots, and shades of brown. A broad, grayish-white fascia is defined by a thin, almost obsolete brown shade from the middle of the costa to the anal angle. The whitish middle fascia is dotted with brown, and a faint line of brown lines the inner border. The ocellus is in the middle of the wing with six or eight black dots and horizontal dashes. The costa is whitish-grey and marked with short brown lines with four larger spots on the outer half. Cilia are fuscous and brown near the apex, while white in the middle. The hindwings are light bronzy-brown, and pale at the base, with a grey underside.
This moth can be distinguished from G. fasciolana by the overall greyish appearance of the forewings and the darker interfascial areas (contrast less with the fasciae). The median fascia are also weakly marked. This species can be distinguished from G. fasciolana by its larger size and browner forewings (Gilligan et al. 2008).
Eggs are laid on the upper surface of leaves near the midrib or vein. Embryos develop into first instar larvae within 5 days. These larvae chew out of the egg membrane and construct a silk structure and feed on leaf tissue. The second-instar larvae then bores into a fresh shoot and finishes its development in this tunnel shoot. The fifth instar larvae then emerge from the twig shelters and move down the tree to construct a silk cocoon in a bark crevice. Pupation then occurs and 8-9 days later an adult emerges. The wings rest in a tentlike position. There can be 4 or 5 generations per year, with the last overwintering as a second-instar larva in a hibernaculum built onto bark or a hollowed bud. The second instar larvae then mature and produce a larger spring generation (Morris 1967).
Potter wasps (Eumenes sp.) have been known to tear open cottonwood shoots and remove cottonwood twig borers from their galleries. There are also parasitic wasps that attack the twig boring larvae: Bracon mellitor (Say), Apanteles clavatus (Provancher), and Agathis sp. Trichogramma minutum (Riley), the egg parasitoid was also collected from twig borer eggs. Predaceous plant bugs (Coreidae) also feed on G. haimbachiana larvae (Morris 1967).
No information available.
The larvae feed on Populus deltoides (cottonwood) primarily in the shoots (and on leaves for early instars) (Morris 1967).
This genus has a primarily Holarctic range with seven species recognized in North America (Alberta, Ontario, Maine to Minnesota, south to Georgia and Texas) (Gilligan et al. 2008, Fernald 1882, Pohl et al. 2010, Morris 1967).
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