Hylurgus ligniperda (Fabr.) 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. Moderately large, 4.0-5.7 mm, black-brown, cylindrical, covered with rather long reddish hairs (Fig. 1). The distinctive, dense hairs are quite thick, and they appear notched at magnifications under 80X. (Actually, at very high magnification (Fig. 8), one can see these hairs are branched.) The elytral apex is convex with a slight indentation, and without teeth or other armature. Hylurgus ligniperda is superficially similar to Hylastes porculus Erichson, a local, nearly hairless species.

Recognizing the Genus. Most similar to Dendroctonus and Tomicus, the genus Hylurgus is not known to occur in North America (Wood 1982). In the key to help screen for Tomicus piniperda (Passoa and Cavey 1993), Hylurgus will key to Tomicus, primarily because both have a 6-segmented funicle. In Wood (1982), specimens of Hylurgus will not go beyond couplet 11 in the generic key, again because of the 6-segmented funicle. The following key (modified form Wood 1982, 1986) will help differentiate Hylurgus from North American bark beetles, including T. piniperda.

Key to Help Screen Hylurgus ligniperda F. from Survey Samples
of North American Scolytidae (Coleoptera):

Figure 1. Habitus of Hylurgus ligniperda Fabricius, lateral view (photo, J.F. Cavey).

Figure 2. Raised base of elytra of Tomicus piniperda L., with granules (from Passoa and Cavey 1993).

1.	Anterior margin of elytra a straight, transverse line, not raised or armed with a number of granules	not Hylurgus
	Anterior margin of elytra raised and armed with a number of granules (Fig. 2); subfamily Hylesininae	see #2
2.	Antennal funicle not 6-segmented or scutellum not visible	not Hylurgus	Figure 3. Antenna of Tomicus piniperda L. with segments of funicle numbered. S = scape, C = club (from Passoa and Cavey 1993).
	Antennal funicle 6-segmented (Fig. 3); scutellum visible	see #3
3.	Procoxae widely separated (Fig. 4a)	not Hylurgus
	Procoxae nearly contiguous (Fig. 4b)	see #4	Figure 4. Bark beetle prosternum with procoxae a. widely separated b. nearly contiguous. C = procoxae, paired arrows denote coxal spacing.
4.	Eye completely divided or deeply emarginate	not Hylurgus
	Eye entire (Fig. 5)	see #5	Figure 5. Head of Tomicus piniperda, showing eye entire ( from Passoa and Cavey 1993).
5.	Elytral interstriae with single rows of erect setae (Fig. 6); procoxae moderately separated; frons with a raised median line for most of length (Fig. 9)	Tomicus piniperda L.
	Elytral interstriae with erect setae abundant, confused, not in rows (Fig. 7); procoxae contiguous; frons with a raised longitudinal tubercle near apex, basal half of frons not armed	Hylurgus ligniperda suspect	Figure 6. Elytra of Tomicus piniperda showing interstriae with single rows of erect setae (from Passoa and Cavey 1993).

Figure 7. Elytra of Hylurgus ligniperda showing confused, erect interstrial setae (photo by John Mitchell and S. Passoa).	Figure 8. Elytral hairs of Hylurgus  ligniperda under SEM, magnification  500X (phot by J. Mitchell and S. Passoa).
Figure 9. Head of Tomicus piniperda showing raised median line on frons (photo by S. Donahue and N. Vandenberg).

adult beetle
Photo by Steve Passoa

[ Back ]