Key to Help Screen Tomicus piniperda (L.)

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.

For more information on Tomicus piniperda (L.) - USDA Forest Service Pest Alert

The following key was designed so that entomologists with little taxonomic experience in bark beetles (Scolytidae) could recognize T. piniperda. Help notes and a glossary follow the key. Although this will produce accurate identifications, it should be emphasized that all T. piniperda determinations need to be confirmed by a specialist. Such caution is important because the ever changing Nearctic scolytid fauna may someday include genera which resemble T. piniperda.

1	Basal margin of elytra armed (Figure 1)	See 2
1	Basal margin of elytra unarmed	Not T. piniperda
2	Eyes not divided or emarginate (Figure 2)	See 3
2	Eyes divided or emarginate	Not T. piniperda	Figure 1.
3	Anterior lateral portions of pronotum with setiferous punctures	See 4
3	Anterior lateral portions of pronotum asperate	Not T. piniperda	Figure 2.	Figure 3.
4	Funicle with 6 segments (Figures 4 and 5; numbered in Figure 5; S = scape; C = club)	See 5
4	Funicle with 5 or 7 segments	Not T. piniperda	Figure 4.	Figure 5.
5	Second row of setae continues uninterrupted through the declivity	Not T. piniperda
5	Second row of setae sparse or absent on the declivity (Figures 6, 7)	T. piniperda	Figure 6.	Figure 7.

Key prepared by
Steven Passoa, USDA/APHIS/PPQ, Northeastern Region
Joe Cavey, USDA/APHIS/PPQ, Northeastern Region

Help notes to Tomicus piniperda key

Couplet 1:
It is easier to see armed elytra when the beetle is viewed "head on." Common scolytids with unarmed elytra are Ips, Orthotomicus, Scolytus, and Xyleborus.

Couplet 3:
For an example of an asperate pronotum, see Wood 1982; page 698, Ips calligraphus, figure 169-1.

Couplet 4:
Don't count the scape or the club. Only the number of segments in the funicle is important. A common genus of scolytids with a 5-segmented funicle is Dendroctonus while Hylurgopinus has a 7-segmented funicle.

Couplet 5:
Some scolytids have a row of setae on the elytra between rows of punctures or striae. On T. piniperda, the second row of setae from the midline (suture) usually does not continue onto the declivity or is represented on the declivity by only a few scattered hairs. Do not confuse short hairs on the declivity of T. piniperda with major setae. When the taxonomic literature describes the second interval as bare, it ignores any short hairs which may be present. Unlike major setae, the short hairs are not in rows (see Figure 6). The best way to examine the declivity is with oblique lighting.

	Figure 8. Typical bark beetle gallery of T. piniperda showing a vertical egg gallery constructed by a pair of adult beetles along with radiating larval galleries (USDA Coop. Econ. Ins. Rpt., 1972).

It is usually necessary to rotate the specimen in order to search for the smooth area. Evaluating the declivity is a difficult character for the non-specialist; it may be necessary to examine a reference specimen of T. piniperda first for practice.

Important notes

Some females of T. piniperda (5-10%) have a more continuous second row of setae on the declivity and might consequently key incorrectly in couplet 5 (S.L. Wood, pers. comm.). Any scolytids that key past couplet 4 in this key should be considered as suspect exotic species.

Description of T. piniperda adult:

• Size: 3.5 to 4.8 mm
• Color: light brown to black depending on maturity. A bicolored form exists where the elytra are reddish brown while the head and thorax are black (Berg, unpublished PPQ notes and specimens in APHIS Port Collection, Baltimore, Maryland).

Glossary

Armed elytra: elytra that have a series of raised semicircular projections (Figure 1).

Asperate pronotum: a pronotum roughened with blunt or pointed grainlike elevations.

Club: enlarged apical segments of the antenna (segments 8-11 on T. piniperda).

Declivity: the portion of the elytra that slopes downward at the rear end of the beetle above the anus.

Elytra: the hardened front wing covers of beetles.

Funicle: that portion of the antenna between the scape and the club (segments 2-7 in T. piniperda).

Scape: the elongate first segment of the antenna.

Setiferous punctures: a pit in the cuticle (skin) with a hair in the center.

Non-target information which may help future survey efforts.

1. Other scolytids found in pine shoots in the northeastern USA with T. piniperda include:
   • Pityophthorus spp. (3 species)
   • Orthotomicus caelatus
2. Other insects found in pine shoots during the T. piniperda survey in the Northeastern USA;
   • Dioryctria spp. (Lepidoptera: Pyralidae)
   • Pissodes spp. (Coleoptera: Curculionidae)
3. Native scolytids that resemble T. piniperda include:
   • Hylastes salebrosus
   • Hylurgopsspp. (various)
4. Scolytids which do not yet occur in the USA that resemble T. piniperda are:
   • Tomicus  spp., for example T. minor
   • Hylurgus ligniperda

Acknowledgments

We thank the following people for their advice in constructing this technical note.

Don Anderson and Natalia Vandenberg, USDA/ARS/SEL
Stephen L. Wood, Brigham Young University
Russ Stewart, USDA/APHIS BATS staff
Robert A. Haack, USDA Forest Service, NCFES
Daniel R. Kucera, USDA Forest Service, NA

The support of the USDA/APHIS/PPQ Northeastern Region and use of the scanning electron microscope and insect collection at Ohio State University are also appreciated.

Photo Credits:
John Mitchell, Ohio State University
Steven Passoa, USDA/APHIS/PPQ
Sara Donahue, USDA/ARS/SEL
Natalia Vandenberg, USDA/ARS/SEL

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