|scientific name Argyresthia goedartella |
Boreal habitats; usually common among birch and alder wherever it is found.
Adults appear in April and some will fly as late as September.
"10-13 mm. Labial palpi golden white; face and head pale ochreous; antennae white ringed with dark brown; scape whitish; thorax and tegula pale golden. Forewings with veins R4 and R5 separate; metallic markings present, apical markings coarse. Forewing shining white with golden reflections, sometimes suffused with pale golden; an outwardly oblique, somewhat curved coppery-golden fascia from base of costa; another similarly colored on the middle of the wing is strongly furcate at costa, and a third inwardly oblique fascia at apical third, parallel with the outer fork of the second fascia, emits a lobe into the apical part of the wing, sometimes connecting with the coppery-golden apex. Hindwings dark gray. Legs brownish white, darker near intersegmental joints. Abdomen grayish fuscous (Forbes 1923: 345; Emmet et al 1996: 80). North American specimens are slightly larger than the European ones and the head and thorax have somewhat lighter color than in the European series" (Busck, 1907: 13).
This is the best known and easiest to distinguish Argyresthia species in Alberta. The golden markings on the forewing are much more prominent than those of A. pygmaeela and A. oreasella, the closest species.
Fully fed larva about 11 mm long. Head shining dark brown, cervical shield brown indistinctly marked with black; body green or pinkish ochreous. The larva overwinters in a shoot or male catkin until late March or April. Tenanted catkins are distorted and frass is ejected trough a hole in the side. In late March or April, the larva descends on a silken thread to pupate under bark, where many sometimes congregate. It may remain there several weeks before pupating. It is not known whether or not it feeds whilst under bark. Pupa is formed in a cocoon under the bark. The pupal stage lasts four to six weeks, in May-June. Adults usually appear in June and last until August, or occasionally September. There is a single generation per year. Adults can be beaten from birch or alder; they fly in afternoon sunshine and also come to light (Forbes 1923: 345; Emmet et al 1996: 80).
Not of concern.
The larva feeds on catkins and shoots of alder (Alnus glutinosa) and birch (Betula) (Busck, 1907: 13).
In North America it is reported from Michigan (Nielsen 1998: 7), Colorado and California, Center Harbor, New Hampshire, and Pecos in Mexico (Busck, 1907: 13). In Canada, it is recorded from British Columbia (Busck, 1907: 13), Alberta (Edmonton, Lac La Biche, Smith) and Saskatchewan (vic. Big River).
I believe one of my trees are infected with this organism. How can I verify, and is the tree dead? It looks like it. How can I prevent it from spreading to the nearby tree?
Vazrick Nazari (2009-09-05)
The species of Argyresthia are usually rare and do not cause any serious damage on either Birch or Alder. Your tree may be suffering from some of the other well known pests that often cause considerable damage; i.e. the Bronze Birch Borer (Agrilus anxius, a beetle) or the Birch leaf miner (Fenusa pusilla, a sawfly). There is plenty of information on the web about these critters that can help you identify them.
Comments are published according to our submission guidelines. The EH Strickland Entomological Museum does not necessarily endorse the views expressed.