Orthotomicus erosus (Wollaston) Screening Aid

From: Cavey, J., Passoa, S. and Kucera D. 1994, Screening Aids for Exotic Bark Beetles in the Northeastern United States. NA-TP-11-94. Northeastern Area: U.S. Department of Agriculture, Forest Service.

General Appearance in a Sample. Length 2.7-3.5 mm; red-brown; anterior portion of pronotum asperate; elytral declivity moderately concave with lateral spines or teeth.

Recognizing the Genus. This species might be keyed to either Orthotomicus or Ips in Bright (1976) or Wood (1982), depending on the workers interpretation of described characters. It is similar to the only North American Orthotomicus, O. caelatus (Eichhoff), a common species throughout the region. Wood (1982) placed O. erosus in the genus Ips, but we are using the old generic name to retain continuity with foreign literature and pest interception records. It is much like Ips latidens (LeConte), which occurs in the NER (S.L. Wood, pers. Commun. 11/5/92). Having four declivital teeth, O. erosus might be confused with Ips pini (Say), the most common species in NER trap samples from the 1993 Pilot Bark Beetle Survey.

Recognizing O. erosus. This exotic pest may be separated from similar NER species in each genus as follows:

Orthotomicus erosus 2nd declivital tooth largest (on female and male), broad for most of its length (Fig. 1).	Ips pini 2nd declivital tooth small; 3rd largest and capitate on male (Fig. 3a); all 4 teeth conical on female (Fig. 3b).
		Figure 1. Elytral apex of Orthotomicus erosus (Woll.).	Figure 2. Antenna of a. O. erosus and b. O. caelatus (Eich.).
Orthotomicus erosus Antennal club with sutures procurved (Fig. 2a). Declivity with 4 teeth.	Orthotomicus caelatus Antennal club with sutures recurved (Fig. 2b). Declivity with 3 teeth (Fig. 4).
		Figure 3. Elytral apex of Ips pini (Say), lateral view of a. male and b. female.
Orthotomicus erosus 2nd declivital tooth largest (on males and females), broad for most of its length (Fig. 1).	Ips latidens 3rd declivital tooth largest on male, conical,tapered from its base to apex (Fig. 5). Granules of frons equally minute.
		Figure 4. Elytral apex of Orthotomicus caelatus, female showing 3 declivital teeth.	Figure 5. Elytral apex of Ips latidens (LeC.) male showing 3 declivital teeth.

Pityogenes and the closely related genus Pityokteines differ from O. erosus in having only 2 or 3 conical teeth on the declivity.

Figures 1, 3, 4, and 5 are modified from Wood (1982).

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