Scolytidae

Figure 32

Figure 33

Figure 34

• Xyleborus Eichhoff (figs. 31, 32): Xyleborus spp. are small (2.0-3.0 mm) and oblong. When viewed from above, the prothorax conceals the head. Like Ips spp., some Xyleborus have irregular teeth or spines on the posterior of the elytra. These insects, however, have a more shallow declivity than Ips and no shelf at the base of the elytra (fig. 31). Xyleborus has a bellshaped pronotum that is wider than the anterior portion of the elytra.

• Dendroctonus frontalis Zimmermann (fig. 33): D. frontalis, the SPB (2.2-4.0 mm), should be easily recognized by the users of this guide. The head is visible from above, with the elevation on either side of the medial frontal groove more pronounced in the male; the female has a ridge on the anterior margin of the pronotum.

• D. terebrans (Olivier) (fig. 34): Its size (5.0-8.0 mm) makes the black turpentine beetle easily recognizable. It has club-shaped antennae and no declivity at the posterior of the elytra, with the pronotum widening posteriorly.

• Ips De Geer: The pine engravers, or Ips spp., have spines lining a declivity on the posterior portion of the elytra. Unlike Xyleborus spp., the engravers have a distinct shelf, or ridge, at the base of the deep declivity. They are larger than other scolytids having a declivity lined with spines.

• I. avulsus (Eichhoff) (fig. 35): Elytral declivity is moderately excavated, with four teeth on each side; the second and third teeth are connected at their base. The apical margin is slightly elevated. Length is 2.1-2.8 mm.

• I. grandicollis (Eichhoff) (fig. 36): Five teeth line the margin of the declivity on each elytra. The center tooth is most prominent. The apical margin is strongly elevated. Length is 3.03.8 mm.

• I. calligraphus (Germar) (fig. 37): There are six teeth on the margin of the declivity. The third tooth is stout and curved downward at the tip. The apical margin is acutely elevated. Length is 4.0-6.0 mm.

Figure 36

Figure 37

Figure 39

Figure 40

• Pityophthorus Eichhoff (fig. 38): The female of this small (1.6 mm) scolytid has long golden hairs on the front of the head; male hairs are shorter and less numerous. The head is covered by the pronotum. There are numerous elevations (asperities) on the pronotum. Antennae are clubbed.

• Crypturgus aleutaceus Schwarz (fig. 39): This is the smallest (0.9 mm) insect associate of the SPB. Head is visible from above, and the antennae have three segments, the third much larger than the others.

• Gnathotrichus materiarius (Fitch) (fig. 40): The prothorax summits well before the middle of this small scolytid (3.0 mm). It is dark brown and has slightly pale elytra. The head is not visible from above. Antennae are clubbed.