Larch Bud Moth - Field Guide to Diseases and Insect Pests of Idaho and Montana Forests

Larch Bud Moth

Zeiraphera improbana (Walker)

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – Western larch. Mainly in high altitude, overstory stands. Distribution. -- Throughout host range.

Damage. – Larvae consume needles and frequently gouge out one side of new shoots. Outbreaks usually last 1 to 2 years with little permanent damage.

Identification. – Look for larvae in needle clusters, needle tubes lined with silk (fig. 122), or webbed needles from May through July. The first four instars are yellow-brown with dark brown heads. The fifth instar is dusky black with an almost black head and is about one-half inch long. Larvae drop to the ground by August and pupate in the duff. Moths fly in August and lay eggs which will overwinter under lichens and in other niches on a tree.
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Figure 122 - Larch Bud Moth larvae
feed in "tubes" made of needle clusters
held together and lined with silk.

Similar damage. – Damage is similar to larch sawfly damage, but larvae are easily distinguished one from the other.

Link to Images in Forestry Images

References.

Furniss, R. L., and V. M. Carolin. 1977. Western For. Insects. USDA Forest Serv., Misc. pub. 1339, 654 p., illus.

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