Aspen twoleaf tier

Distribution

Canada

Micro-habitat(s)

Leaf

Damage, symptoms and biology

The aspen twoleaf tier is easy to detect; typically, throughout the larval stage, the larvae construct a shelter by binding two leaves together.

Newly hatched larvae begin by feeding on the inner side of a rolled-up leaf and then move to feed on the outside. Older larvae feed on the side of the leaves and construct flattened cases made from two leaves bound together with silk webbing. Once the larval stage has been completed, the insects fall to the ground and pupate.

Although a serious infestation may result in the complete defoliation of the host tree, infestations rarely cause severe damage because they are short-lived, with populations quickly controlled by natural factors.

Life cycle (East of the Rockies)

Other information

The aspen twoleaf tier occurs mainly in the Prairie provinces and in Ontario and Quebec. In Ontario, major outbreaks occurred in the late 1950s and early 1970s. In Quebec, aspen twoleaf tier populations are often associated with the large aspen tortrix. Populations apparently increased substantially between 1970 and 1975. More recently, occasional outbreaks have occurred, always in association with outbreaks of the large aspen tortrix, making it difficult sometimes to assess the extent of the damage caused by the aspen twoleaf tier.

No specific control measures are recommended since damage from the species is relatively minor, with outbreaks being short lived.

Main host(s)

Eastern cottonwood, trembling aspen