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Scolytus multistriatus (Scolytidae)
Dutch elm beetle
Members of the genus Scolytus are readily recognized by the "sawed-off"
rear end of the abdomen (= posterior ventral concavity).
Adults:
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2.2 to 3.0 mm long. Presence of a prominent spine on the second abdominal segment of S. multistriatus readily separates this species from S. regulosus which is unarmed and is the only other hardwood infesting western scolytid.
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Larvae:
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Typical scolytid larvae.
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Damage:
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S. multistriatus is a vector of Dutch elm disease (DED) fungus, Ceratocystis ulmi. Transmission of DED occurs during maturation feeding of adults on twigs of host trees. After maturation feeding and mating in the twig feeding phase, the females attack the main tree bole where they construct a longitudinal egg gallery. Larval galleries fan out on both sides, often in a striking regular pattern.
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Principal Hosts:
Ulnus spp.
Economic Importance:
DED has decimated the majority of elms in the eastern U.S. and Canada, and its insect vector S. multistriatus is now widespread in the west; therefore further spread of this destructive disease seems inevitable.
References and Links:
EAG: 491-498, 512-514; FC: 403.
Additional Images:
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