Forest Pest Insects in North America: a Photographic Guide

Siberian moth

Dendrolimus sibiricus TschetvericKov (Lepidoptera: Lasiocampidae)

Orientation to pest

Siberian moth, Dendrolimus sibiricus TschetveriKov, is a defoliator of great importance in northern Asia, causing widespread, extensive mortality to various conifers during outbreaks. It does not occur in North American but is a species of great concern. Typically, this moth has a two-year life cycle, spread over parts of three calendar years. Adults fly and lay eggs from late June to mid-July. Eggs are laid in chains or clusters on needles or branches. In their first year, larvae feed until they reach the second or third instar and then overwinter in the forest litter. In year two, partly grown larvae continue to feed, at a slower rate, until they are in the fifth to seventh instar, at which stage they overwinter. In their third calendar year, larva feed until mature in spring and pupate inside cocoons fixed to trees. Adult moths appear in late June and July and may fly several kilometers before laying her eggs. Outbreaks occur at about 10 year intervals and last 2-3 years. An outbreak can defoliate thousands of hectares and affect entire forests. Since the insect has overlapping generations and life cycles extending more than one growing season, it can defoliate stands in the spring, summer and fall, but most defoliation occurs in spring when older larvae feed.

Hosts commonly attacked

Larvae of D. sibiricus feed on the foliage of more than 20 species of conifers in northern Asia, especially on species of larch (Larix ) and fir (Abies), but also on less favored hosts such as five-needle and two-needle pines (Pinus) and spruce (Picea). Injury is greatest to species of fir and certain pines (e.g., Pinus koraiensis Sieb. et Zucc. and Pinus sibirica Du Tour). Although larch species are the most favored hosts, they can re-foliate and are seldom killed. It has been shown that this polyphagous species can develop on a wide range of European and North American conifers.

Distribution

The Siberian moth does not occur in North America, but is considered a very high risk invader because of its potential for invasion and the magnitude of likely damage. Boreal and subalpine forests in North America would be at risk. Its current distribution includes Siberia (Russia), northeastern China, northern Mongolia, and part of North Korea.

Images of Siberian moth

Male Siberian moth Natalia Kirichenko, Bugwood.org 768x512 / 1536x1024
Egg mass of Siberian moth John H. Ghent, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Larva of Siberian moth John H. Ghent, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Figure 1. Male Siberian moth, Dendrolimus sibericus Figure 2. Egg mass of Siberian moth Figure 3. Larva of Siberian moth
Pupal cocoons of Siberian moth John H. Ghent, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Stand of Siberian larch defoliated by Siberian moth John H. Ghent, USDA Forest Service, Bugwood.org 768x512 / 1536x1024
Figure 4. Pupal cocoons of Siberian moth Figure 5. Stand of Siberian larch (Larix sibirica Ledeb.) defoliated by Siberian moth

Important biological control agents related to this pest species

More than 40 species of parasitoids are known to attack D. sibiricus, of which the most important are the egg parasites Telenomus tetratomus (Thomson) (Scelionidae) and Ooencyrtus pinicola Matsumura (Encyrtidae), the larval parasite Rogas dendrolimi Matsumura (Braconidae), and the larval-pupal parasites Blepharipa schineri (Mesnil.), Blepharipa pratensis Meigen and Lespesia frenchii (Williston) (all Tachinidae).

Web links for information on Siberian moth

Articles

University of Massachusetts, PSIS/Entomology USDA Forest ServiceUniversity of Georgia Center for Invasive Species and Ecosystem HealthUniversity of Georgia