|scientific name Scolytus multistriatus |
common name Smaller european elm bark beetle.
These beetles spend most of their lives around their host trees (Ulmus spp.). Adults will be found on the trees themselves while larvae are always in the wood.
Overwintering generations will emerge as adults in June or July, while their progeny will emerge either in August and September, or overwinter. Some of the adults that emerge in August and September may breed and giving rise to another generation of overwintering larval individuals (Bright 1976).
Adults can be about 2.2 - 3.0mm long and are reddish brown in colour. Both males and females will have a cylindrical and narrow spine arising from the anterior edge of the 2rd abdominal sternite (Bright 1976, LaBonte et. al. 2003). Teeth are usually present on the posterior-lateral margins of the 2nd to 4th abdominal sternites (LaBonte et. al. 2003).
In Canada, these beetles may produce one and a half generations each year. They overwinter as larvae and adults will emerge in June or July. These adults will mate and most of these progeny will finish development by August and September. Some of them, however, may overwinter as larvae before emerging in June/July the following year. Adults that emerge in late summer are also capable of mating and oviposition to produce another generation of overwintering larvae (Bright 1976).
Both adults and larvae feed on Elm. The adults generally attack small twigs and the larvae feed on the wood in the trunk (Bright 1976). Large feeding damage may kill the twig or even girdle the trunk.
These beetles are European in origin but have accidentally been introduced in North America (Bright 1976). They can now be found in most of Eastern Canada, and is gradually spreading westwards. Adults of S. multistriatus have been collected in Alberta.
While the feeding behaviors of these beetles are not extremely damaging to host trees, they are vectors of the fungus, Ophiostoma ulmi (Buisman) that is responsible for causing Dutch Elm Disease (Bright 1976). As such, these beetles are considered pests and many cities are monitoring their populations (Bright 1976).
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