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Bark Beetles of Northeastern Pines: An Illustrated Guide to Common Species

Authors:

Abstract and Figures

Bark beetles (Coleoptera: Curculionidae: Scolytinae) are one of the most economically significant forest pests. Many species, both foreign and native, cause considerable damage each year to native pines in New England and New York. Southern pine beetle (SPB), Dendroctonus frontalis, is present in the Northeastern United States and predicted to spread throughout the region in the coming decades. It is relatively easy to identify this aggressive killer of pines in attacked trees by its unique larval gallery pattern or resin buildup on the outer bark at attack sites above breast height on the tree bole. However, a suite of other bark beetles that live in the phloem can also colonize either freshly killed trees, such as those attacked by SPB, or stressed and dying trees. The presence of these other bark beetles may cause some confusion during forest health surveys and lead to misdiagnosis of what killed a tree. Detection and monitoring trapping have also expanded because SPB is now in the Northeast. Although these traps are baited with a combination of beetle pheromones and tree host volatiles that target SPB, these traps also attract other bark beetle species, including many of the species found during tree inspections. Forest health professionals and natural resource managers will encounter bark beetle species other than SPB during either visual surveys of trees or trapping efforts. Because of this, bark beetle identification tools would be useful for forest health surveyors. This guide provides a key to common phloem-inhabiting bark beetles of pine, biological information on select species, and detailed photographs of common species found in the Northeastern U.S.
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United States Department of Agriculture
Forest
Service
Eastern Region
State and Private Forestry R9-PR-001-20 August 2020
Bark Beetles of
Northeastern Pines
An Illustrated Guide to Common Species
Acknowledgments:
We would like to thank Robert Rabaglia (USDA Forest Service, State & Private
Forestry, Forest Health Protecon, Washington Oce) for reviewing and providing
valuable comments on a dra of this document.
Cover photo: The underside of bark peeled from a pine tree killed by the southern
pine beetle (Dendroctonus frontalis), showing the typical serpenne feeding galleries.
(Courtesy photo by W.H. Benne, USDA Forest Service, Bugwood.org)
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Bark Beetles of
Northeastern Pines
An Illustrated Guide to Common Species
Marc F. DiGirolomo and Kevin J. Dodds
Published by:
Forest Service
Eastern Region
State and Private Forestry
626 East Wisconsin Avenue
Milwaukee, WI 53202
hps://www.fs.usda.gov/r9
R9-PR-001-20
August 2020
Table of Contents
Introducon ............................................................................................................................ 1
Basic Anatomy of a Bark Beetle ..............................................................................................2
Quick Habitus Reference ........................................................................................................4
Key to Species in this Guide ....................................................................................................6
Dendroctonus frontalis Zimmermann .................................................................................10
Dendroctonus terebrans (Olivier) ........................................................................................12
Dendroctonus valens LeConte .............................................................................................14
Ips avulsus (Eicho) .............................................................................................................16
Ips calligraphus (Germar) ....................................................................................................18
Ips grandicollis (Eicho) .......................................................................................................20
Ips pini (Say) .........................................................................................................................22
Orthotomicus caelatus (Eicho) ..........................................................................................24
Hylastes opacus Erichson ..................................................................................................... 26
Hylastes porculus Erichson ..................................................................................................28
Hylastes tenuis (Eicho).......................................................................................................30
Hylurgops pinifex (Fitch) ......................................................................................................32
Other Species in Northeastern Pines Not Treated in This Guide .......................................... 34
Glossary of Technical Terms .................................................................................................35
Selected Bibliography ........................................................................................................... 36
Distribution of Native Pines in New England and New York
Pinus banksiana - Jack Pine Pinus echinata - Shortleaf Pine
Pinus resinosa - Red Pine Pinus rigida - Pitch Pine
Pinus strobus - Eastern White Pine Pinus virginiana - Virginia Pine
Figure 1.—Distribution of native pines in New England and New York. (Source: Prasad, A.M.; Iverson, L.R. 2003. Little’s range and FIA
importance value database for 135 eastern US tree species. RWU NE–4153. Delaware, OH: U.S. Department of Agriculture, Forest Service,
Northeastern Research Station. http://www.fs.fed.us/ne/delaware/4153/global/littlea/index.html. (28 January 2020).
1
Distribution of Native Pines in New England and New York Introduction
Bark beetles (Coleoptera: Curculionidae: Scolynae) are
one of the most economically signicant forest pests.
Many species, both foreign and nave, cause considerable
damage each year to nave pines in New England and New
York (gure 1—facing page).
Southern pine beetle (SPB), Dendroctonus frontalis, is
present in the Northeastern United States and predicted
to spread throughout the region in the coming decades. It
is relavely easy to idenfy this aggressive killer of pines
in aacked trees by its unique larval gallery paern (Cover
photo) or resin buildup on the outer bark at aack sites
above breast height on the tree bole (gure 2). However, a
suite of other bark beetles that live in the phloem can also
colonize either freshly killed trees, such as those aacked
by SPB, or stressed and dying trees. The presence of these
other bark beetles may cause some confusion during forest
health surveys and lead to misdiagnosis of what killed a
tree.
Detecon and monitoring trapping (gure 3) have also
expanded because SPB is now in the Northeast. Although
these traps are baited with a combinaon of beetle
pheromones and tree host volales that target SPB, these
traps also aract other bark beetle species, including many
of the species found during tree inspecons. Forest health
professionals and natural resource managers will encounter
bark beetle species other than SPB during either visual
surveys of trees or trapping eorts. Because of this, bark
beetle idencaon tools would be useful for forest health
surveyors. This guide provides a key to common phloem-
inhabing bark beetles of pine, biological informaon
on select species, and detailed photographs of common
species found in the Northeastern U.S.
Limitations of this Guide
This guide is one tool in the toolbox of resources for
idenfying bark beetles. The species detailed here are
the Scolynae most likely to be seen inhabing stressed
and recently killed pine trees in the Northeastern United
States. It is also likely that several other species may be
encountered during tree or trapping surveys, especially
those infesng branches, twigs, and cones. Surveyors
may see phloem-inhabing beetles in the Crypturgus,
Dryocoetes, Hylurgus, Hypothenemus, Pityogenes,
Pityophthorus, Polygraphus, and Tomicus genera. Sapwood-
inhabing species, including those in the Euwallacea,
Gnathotrichus, Trypodendron, Xyleborinus, Xyleborus, and
Xylosandrus genera, are also likely to be encountered at
mes. Representave images of these genera can be found
on page 34. We recommend consulng the resources
listed on page 36 for more informaon on the diversity,
distribuon, and biology of bark and ambrosia beetles in
the Northeast.
Figure 2.—Dendroctonus frontalis-infested pine with resin buildup
at attack sites.
Figure 3.—Multiple-funnel trap deployed in a recently harvested
pitch pine stand in the Montague Plains Wildlife Management
Area in Massachusetts.
2
Basic Anatomy of a Bark Beetle
See page 35 for a glossary of technical terms.
3
Head
4
Quick Habitus Reference
Dorsal View
A
B C
D
EF
GH
I
J
K
L
Dorsal habitus of species treated in this guide. All are at the same scale. (A) Dendroctonus frontalis, (B) D. terebrans,
(C) D. valens, (D) Ips avulsus, (E) I. calligraphus, (F) I. grandicollis, (G) I. pini, (H) Orthotomicus caelatus, (I) Hylurgops pinifex,
(J) Hylastes opacus, (K) Hylastes porculus, (L) Hylastes tenuis.
5
Lateral View
A
B
C
H
I
D
E
F
G
J
K
L
Lateral habitus of species treated in this guide. All are at the same scale. (A) Dendroctonus frontalis, (B) D. terebrans,
(C) D. valens, (D) Ips avulsus, (E) I. calligraphus, (F) I. grandicollis, (G) I. pini, (H) Orthotomicus caelatus, (I) Hylurgops pinifex,
(J) Hylastes opacus, (K) Hylastes porculus, (L) Hylastes tenuis.
6
Key to Species in this Guide
1. Head obviously visible from above (A, B) ..................................................................................................................... 2
1’. Head not or only slightly visible from above (C, D) ...................................................................................................... 5
A B
C D
2(1). Antennal club aened (A); lateral prosternal area without sharply elevated ridge (B) ......................................... 3
2’. Antennal club conical (C); lateral prosternal area with sharply elevated ridge from coxa to anterior margin (D) ....... 5
A B C D
7
3(2). Frons with a deep frontal groove and two large () or small (♀) lateral tubercles (A, B); size small (2.0–3.2 mm)
....................................................................................................................................................... Dendroctonus frontalis
3’. Frons without groove or tubercles (C); size large (5.0–9.0 mm) .................................................................................. 4
4(3). Mature color black, pronotal punctures more coarse (A) ...................................................Dendroctonus terebrans
4’. Mature color red, pronotal punctures less coarse (B) ................................................................. Dendroctonus valens
5(1 or 2). Antennal club conical (A) .................................................................................................................................. 6
5’. Antennal club aened (B) or obliquely truncate (C) .................................................................................................. 9
A
B
C
A B C
A B
8
Key to Species in this Guide (continued)
6(5). Pronotal punctures more or less uniformly large (A) ............................................................................................... 7
6’. Pronotal punctures consisng of intermixed large and small sizes (B) ..............................................Hylurgops pinifex
7(6). Lower frons with a sharply elevated median carina (A); size large (3.8–5.0 mm) .........................Hylastes porculus
7’. Frons lacking a carina (B); size small (2.0–3.0 mm) ..................................................................................................... 8
8(7). Pronotum (in dorsal view) with sides evenly rounded to nearly parallel, especially in basal third (A); body more
slender ........................................................................................................................................................ Hylastes tenuis
8’. Pronotum (in dorsal view) more rounded and with an obvious constricon toward anterior end (B); body more
robust ....................................................................................................................................................... Hylastes opacus
A B
AB
AB
9
9(5). Antennal club aened (A), sutures procurved or bisinuate; elytral declivity broadly excavated (B), armed by
4 to 6 major spines, all of which are placed along summit of lateral margin ................................................................. 10
9’. Antennal club obliquely truncate (C), sutures recurved; elytral declivity steeper, less strongly excavated (D), the
third tooth displaced mesally, not on summit of declivital margin (E) .......................................... Orthotomicus caelatus
Declivital
Margin
10(9). Lateral margin of declivity armed by 4 pairs of spines (A) ................................................................................... 11
10’. Lateral margin of declivity armed by 5 pairs of spines (B) ...................................................................Ips grandicollis
10’’. Lateral margin of declivity armed by 6 pairs of spines (C) .................................................................Ips calligraphus
11(10). Margin along apex of elytra short (A); declivital spines smaller; size smaller (2.1–2.8 mm) ............... Ips avulsus
11’. Margin along apex of elytra longer, more projecng and shelf-like (B); declivital spines larger; size larger
(3.3–4.3 mm) ........................................................................................................................................................... Ips pini
12
3
4
5
6
1
2
3
4
5
AB
BA C ED
A B C
3rd Tooth
1
2
3
4
10
Dendroctonus frontalis Zimmermann
Southern Pine Beetle
11
Biology
Dendroctonus frontalis can aack and kill healthy trees, which is unusual for
bark beetles in the Northeast. Females locate a potenal host and begin to
build galleries. They emit aggregaon pheromones that, combined with tree
volales from fresh aacks aract males and addional females to the host
tree. If this mass aack is successful, the beetles will overcome the tree’s resin
defenses, mate, and begin laying eggs in brood galleries. Females may then
reemerge from the tree and proceed to aack a new host tree. As larvae feed
and develop, expanding the gallery network, they gradually work toward the
outer bark where they form a pupal cell. The pupae change into callow adults,
which remain within the bark up to 2 weeks while their integument hardens and
darkens. New brood adults then bore an exit hole directly out of the tree and
typically disperse to aack another tree. It is not known how many generaons
may occur during a season in the Northeast.
Northeastern Hosts
Common/likely: Pinus banksiana (jack pine), Pinus echinata (shortleaf pine),
Pinus resinosa (red pine), Pinus rigida (pitch pine), Pinus strobus (eastern
white pine), Pinus virginiana (Virginia pine); Uncommon/reported: Picea abies
(Norway spruce), Picea rubens (red spruce), Tsuga canadensis (eastern hemlock)
Gallery
Aacking beetles create elongate, winding, S-shaped tunnels (galleries) almost
enrely in the phloem, scoring and staining the xylem but not engraving it.
Galleries oen branch, connect, or cross one another and are packed with frass.
The diameter of the gallery is slighter greater than the width of the parent, and
averages around 30 cm in length. Eggs are alternately deposited in small niches
laterally along the length of the gallery. First instar larvae mine a thin, uniform
tunnel about 1 cm approximately perpendicular to the egg gallery. It then
widens abruptly, forming a short, irregular oval, within which feeding connues
and the remaining instars are passed. This chamber is within the phloem and
generally visible on bark peeled from an infested tree. On trees with thick
phloem, it may be harder to observe without peeling into this ssue.
Identication
This species can readily be separated from other northeastern-pine inhabing members of the genus by its much smaller size
and by the deep frontal groove on the frons of both sexes and large protuberances on the frons of males. The D. frontalis gallery
paern is unique to northeastern bark beetles and can be used to diagnose its presence within a tree. Its habit of aacking
healthy trees is also unique in the Northeast.
Length 2.0–3.2 mm (average about 2.8 mm); head generally visible from above; antennal club strongly aened with three
procurved sutures; mature color light brown to dark brown to nearly black; deep median groove on frons between eyes with
males bearing prominent elevated protuberances on either side of the groove; declivity is steeply sloped and rounded; hair-like
vesture is relavely abundant and rather long.
Winding, S-shaped parental galleries of
Dendroctonus frontalis.
Dendroctonus frontalis, Flight Phenology, Long
Island, New York, 2014.
♂ ♂ ♀
Dendroctonus frontalis male frons and tubercles (left pair) and Dendroctonus frontalis female frons and tubercles (right pair).
12
Dendroctonus terebrans (Olivier)
Black Turpentine Beetle
13
Biology
Two species of turpenne beetles occur in porons of the Northeastern
U.S.: Dendroctonus terebrans (black turpenne beetle), generally found
in the Southeastern U.S., and Dendroctonus valens (red turpenne
beetle), a species with a larger distribuon that includes northern
porons of the Northeastern U.S. The distribuon of these species does
occasionally overlap in coastal areas from New Jersey to Massachuses,
but no hybridizaon has been reported.
Generally, D. terebrans is found colonizing the lower boles (usually
below 6 ) and roots of stressed or recently dead trees as well as freshly
cut stumps. Females and males enter the host and begin excavang
the gallery where eggs will be laid. Large globs of reddish resin are
oen found surrounding the site of an aack. Galleries are made in
the phloem and are straight with eggs laid on one side. Larvae feed
gregariously in groups and move away from the brood gallery. Pupaon
occurs in the phloem and/or bark.
Northeastern Hosts
Pinus echinata (shortleaf pine), Pinus rigida (pitch pine), Pinus strobus
(eastern white pine), Picea rubens (red spruce)
Gallery
There can be
substanal variaon
in D. terebrans egg
galleries. The most
commonly encountered
gallery is one that is
longitudinal, with eggs
laid along the edge of
one side. The gallery
is formed below the
aack site and can
extend up to 12 in or
more.
Identication
This species is very closely related to D. valens, but they do not overlap
over most of their distribuons. Where they do coexist, the adults can
be separated by body color (D. terebrans = blackish, D. valens = reddish);
by the larger punctures on the pronotum of D. terebrans (especially
evident on the lateral areas of the pronotum); by the larger and more
abundant granules on the declivity of D. terebrans; and (with cauon) by
their distribuons. Within trees, D. terebrans can be diagnosed by aack
locaons (basal porons of trees) and large amounts of resin produced at
the aack site. D. terebrans and D. valens both colonize the same porons
of hosts, so where both species occur, it is not possible to denively
idenfy the beetle based on galleries or host colonizaon paerns.
Length 5.0–8.0 mm; head generally visible from above; antennal club
strongly aened with three procurved sutures; mature color black;
declivity is steeply sloped and rounded, surface shining and granulate;
punctures on pronotum coarser than on D. valens; hair-like vesture
moderately abundant, longer on declivity.
Relative size of ve northeastern Dendroctonus
species. Top to bottom: D. terebrans, D. valens, D.
rupennis*, D. simplex*, D. frontalis. (*not treated in
this guide)
Egg galleries and gregarious larval feeding area of
D. terebrans.Dendroctonus terebrans, Flight Phenology,
Long Island, New York, 2017.
Dendroctonus terebrans, frons.
14
Dendroctonus valens LeConte
Red Turpentine Beetle
15
Biology
The biology and habits of D. valens are very closely related
to those of D. terebrans. Like D. terebrans, this species
typically aacks large, old, weak, or injured trees as well as
freshly cut logs or stumps. Because D. valens is considered
a secondary pest, mortality and outbreaks are uncommon.
D. valens can be associated with more aggressive bark
beetle species and may hasten mortality of trees aacked
by a primary pest, such as D. frontalis. Aacks are iniated
at ground level by burrowing into the bole and root collar,
forming large, reddish-brown pitch tubes. Aack sites and
galleries, even on heavily infested trees, are typically found
below breast height on the tree bole.
Northeastern Hosts
Pinus echinata (shortleaf pine), Pinus resinosa (red pine),
Pinus rigida (pitch pine), Pinus sylvestris (Scots pine), Pinus
strobus (eastern white pine), Pinus virginiana (Virginia
pine), Larix laricina (tamarack), Picea glauca (white spruce),
Picea abies (Norway spruce), Picea rubens (red spruce)
Gallery
Galleries are quite variable for this species. The entrance
tunnel extends upward a short distance aer reaching the
cambium and may connue upward if excessive pitch is
encountered. It may also curve downward toward the roots.
The egg gallery can range in shape from linear to branching
or even an irregular, broad cave. It is possible to observe all
gallery types within a single tree. Eggs are deposited along
the gallery in groups of 10 to 40 or more and loosely packed
in frass. Larvae mine gregariously, forming a cavity in the
phloem in an irregular paern, but generally away from the
egg gallery, lling the large cavity with frass.
Identication
This species is very closely related to D. terebrans. They
can be separated by the body color of mature adults, by
the much smaller punctures on the pronotum (especially
evident on the lateral areas of the pronotum), by the
smaller and less abundant granules on the declivity, and
(with cauon) by the distribuon.
Length 5.3–9.0 mm; head generally visible from above; antennal club strongly
aened with three outward curving sutures; mature color reddish brown;
declivity is steeply sloped and rounded, surface shining and granulate;
punctures on pronotum less coarse than on D. terebrans; hair-like vesture
moderately abundant, longer on declivity.
Irregular cave style (left) and vertical linear style (right) egg
galleries of D. valens.
Dendroctonus valens, Flight Phenology, Central Massachusetts,
2014.
Dendroctonus valens, frons.
16
Ips avulsus (Eichoff)
Small Southern Pine Engraver
17
Biology
Like other northeastern Ips species, Ips avulsus usually
aacks fallen, cut, or generally stressed trees and limbs.
I. avulsus is oen associated with trees being aacked by
Dendroctonus spp., which may hasten tree mortality. It
usually prefers the tops and larger limbs of trees.
Northeastern Hosts
Pinus echinata (shortleaf pine), Pinus rigida (pitch pine),
Pinus strobus (eastern white pine), Pinus virginiana
(Virginia pine)
Gallery
Parental galleries are Y-shaped, longitudinal tunnels
engraved in the phloem and xylem. Eggs are deposited
along this tunnel, and larvae feed laterally. Very similar to
Ips pini galleries (page 23).
Identication
This species is disnguishable from other northeastern-pine
inhabing members of the genus by its four pairs of spines
on the declivity (same as I. pini), by its smaller size, and by
the wide but short (not projecng as much as I. pini) margin
at the p of the elytra. I. avulsus is the smallest Ips species
found in the Northeast.
Length 2.1–2.8 mm; head generally not visible from above;
mature color dark reddish brown; strongly aened
antennal club with two wavy sutures; vesture of ne, long,
sparse hairs more abundant on sides and declivity; declivity
moderately sloping and strongly excavated, bordered with
four pairs of relavely small spines; margin at p of elytra
wide and feebly projecng.
Ips avulsus, elytral declivity.
Comparison of apical elytral margin of Ips spp. (Top to bottom: I.
calligraphus, I. grandicollis, I. pini, and I. avulsus)
Ips avulsus, Flight Phenology, Long Island, New York, 2017.
18
Ips calligraphus (Germar)
Six-Spined Pine Engraver
19
Six-Spined Pine Engraver Biology
Like other Ips species in the region, Ips calligraphus is oen
found in recently dead trees or downed wood. While rare, I.
calligraphus can aack living trees and is typically found on
lower bole posions. This species generally aacks thick-
barked, fallen trees or logs.
Northeastern Hosts
Pinus banksiana (jack pine), Pinus echinata (shortleaf pine),
Pinus resinosa (red pine), Pinus rigida (pitch pine), Pinus
strobus (eastern white pine), Pinus sylvestris (Scots pine),
Pinus virginiana (Virginia pine)
Gallery
Typically four (but can be from one to ve) parental
galleries extend longitudinally above and below a central
nupal chamber, forming an X- or H-shaped egg gallery.
Larval feeding galleries are moderately long and extend
from the parental tunnels, enlarging as they grow.
Identication
This species is disnguishable from other northeastern
pine-inhabing members of the genus by its six pairs of
spines on the declivity, by its larger size, and by the narrow
margin at the p of the elytra. Ips calligraphus is the largest
Ips species found in the Northeast.
Length 3.8–5.9 mm; head generally not visible from above;
mature color dark reddish brown; strongly aened
antennal club with two wavy sutures; vesture of ne, long,
sparse hairs more abundant on sides and declivity; declivity
moderately sloping and strongly excavated, bordered with
six pairs of spines; margin at p of elytra narrow.
Ips calligraphus, Flight Phenology, Long Island, New York, 2017.
Ips calligraphus, elytral declivity.
X-shaped parental galleries and larval feeding tunnels of I.
calligraphus.
20
Ips grandicollis (Eichoff)
Eastern Five-Spined Ips
21
Biology
Ips grandicollis is generally considered a secondary species
that colonizes stressed or recently dead trees as well as
other downed wood. On rare occasions in the Northeast, I.
grandicollis can aack apparently healthy trees. These trees
are oen drought stressed. This species prefers large limbs
and upper tree boles. Male beetles iniate aack and form
a brood chamber, where three to ve brood galleries iniate
and then radiate outward.
Northeastern Hosts
Pinus banksiana (jack pine), Pinus echinata (shortleaf pine),
Pinus resinosa (red pine), Pinus rigida (pitch pine), Pinus
strobus (eastern white pine), Pinus sylvestris (Scots pine),
Pinus virginiana (Virginia pine)
Gallery
Similar to those of I. calligraphus, but with smaller diameter
tunnels consistent with the smaller size of the adult beetles.
Egg galleries run longitudinally and form a Y or X shape.
Identication
This species can be separated from other northeastern-pine
inhabing Ips by its ve pairs of declivital spines and by the
width of the margin at the p of the elytra (narrower than I.
pini and wider than I. calligraphus).
Length 2.9–4.6 mm; head generally not visible from above;
mature color dark reddish brown; strongly aened
antennal club with two wavy sutures; vesture of ne, long,
sparse hairs more abundant on sides and declivity; declivity
moderately sloping and strongly excavated, bordered with
ve pairs of spines; margin at p of elytra moderately
narrow.
Ips grandicollis, Flight Phenology, Central Massachusetts, 2014.
Ips grandicollis, elytral declivity.
X- and Y-shaped parental galleries of I. grandicollis.
22
Ips pini (Say)
Pine Engraver Beetle
23
Biology
Similar to other northeastern Ips species, Ips pini usually
aacks fallen, cut, or generally stressed trees and limbs.
This species is oen associated with trees being aacked by
Dendroctonus spp., which may hasten tree mortality. It also
usually prefers the tops and larger limbs of trees.
Northeastern Hosts
Pinus banksiana (jack pine), Pinus resinosa (red pine), Pinus
rigida (pitch pine), Pinus strobus (eastern white pine), Pinus
sylvestris (Scots pine), Pinus virginiana (Virginia pine), Picea
glauca (white spruce), Picea abies (Norway spruce), Picea
rubens (red spruce)
Gallery
Parental galleries are Y-shaped, longitudinal tunnels
engraved in the phloem and xylem. Eggs are deposited
along this tunnel, and larvae feed laterally.
Identication
This species can be separated from other northeastern-pine
inhabing Ips by its four pairs of spines on the declivity and
by its relavely long margin at the p of the elytra.
Length 3.3–4.3 mm; head generally not visible from above;
mature color dark reddish brown to nearly black; strongly
aened antennal club with two wavy sutures; vesture
of ne, long, sparse hairs; declivity moderately sloping and
strongly excavated, bordered by four pairs of spines; margin
at p of elytra long.
Ips pini, Flight Phenology, Southern Maine, 2009.
Ips pini, elytral declivity.
Y-shaped parental galleries and larval tunneling of I. pini.
24
Orthotomicus caelatus (Eichoff)
25
Biology
Adults breed mainly in the bole and branches of recently
dead, weakened, or stressed trees as well as stumps of cut
trees. Most commonly found in the thick bark of the lower
bole. Oen accompanies aggressive aacking species (such
as SPB) as a secondary associate arriving soon aer tree
death.
Northeastern Hosts
Any species of Pinus (pine), Picea (spruce), or Larix (larch)
within its range.
Gallery
A slightly radial parental gallery is constructed in the
cambium with short egg galleries. Larvae mine in the
sapwood. Pupaon takes place in either chambers in the
inner bark or in pits in the sapwood.
Identication
Somewhat similar to members of the genus Ips but can be
separated by the more steeply sloped and less excavated
declivity with the third spine disnctly inside the border
of the excavaon, the obliquely truncated antennal club
(looks like the p was sliced o at an angle), and the poorly
developed margin at the p of the elytra.
Length 2.4–3.3 mm; head generally not visible from above;
mature color very dark reddish brown; vesture hair-like,
inconspicuous; antennal club obliquely truncate with two
inward curving sutures; declivity abrupt and steeply sloped,
broadly excavated; three major spines present on declivity,
although there are several addional nodules and bumps
along the border of the declivital excavaon; spine number
three disnctly inside the border of the excavaon; margin
at p of elytra poorly developed.
Orthotomicus caelatus, Flight Phenology, Central Massachusetts,
2014.
Orthotomicus caelatus, elytral declivity.
Orthotomicus caelatus, elytral declivity, location of third spine.
26
Hylastes opacus Erichson
27
Biology
Exoc. Not extensively studied in North America. In Britain,
its biology has been described as similar to Hylastes ater.
Creates egg tunnels in stumps and, more oen, in roots of
host species. It can become an important pest of replanted
conifers aer harvests where the beetles feed in the root
collar region of weak or poorly planted young trees and can
kill vigorous growing plants when populaons are high.
Northeastern Hosts
In Britain, hosts are a variety of species of Pinus (pine),
Picea (spruce), and rarely, Larix (larch)
Gallery
Similar to those of Hylurgops pinifex but with smaller
tunnels corresponding to its smaller size.
Identication
Easily separated from H. porculus by the absence of a
median ridge on the lower frons and by its smaller size.
Disnguished from H. tenuis by the shape of the pronotum,
which is disnctly constricted in front when viewed from
above.
Length 2.5–3.0 mm; elongate; head generally slightly visible
from above; mature body color very dark brown to black,
with antennae and legs typically reddish brown; antennal
club conical with three straight sutures, rst segment of
club longer than others; pronotum about as long as wide,
widest near the middle and disnctly constricted toward
the front; declivity evenly convex and steep; vesture of
short, erect, hair-like bristles, somewhat longer and more
abundant on declivity.
Hylastes opacus, Flight Phenology, Central Massachusetts, 2014.
Hylastes opacus, frons, frontal carina absent.
28
Hylastes porculus Erichson
29
Biology
Breeds in phloem ssues of stumps and roots (occasionally
logs) of hosts.
Northeastern Hosts
Pinus banksiana (jack pine), Pinus echinata (shortleaf pine),
Pinus resinosa (red pine), Pinus rigida (pitch pine), Pinus
strobus (eastern white pine), Pinus sylvestris (Scots pine),
Pinus virginiana (Virginia pine)
Gallery
Simple or branching egg tunnels in phloem ssues, which
may slightly engrave the xylem. Eggs are placed in niches
and larvae mine phloem ssues aimlessly. Larval tunnels can
usually be seen in the phloem when the bark is peeled back.
The random larval tunneling eventually renders the gallery
paerns indisnguishable.
Identication
This species can be separated from other northeastern-pine
inhabing members of Hylastes by its larger size and by
the presence of a median longitudinal ridge located on the
lower frons midway between the base of the eyes and the
mouth.
Length 3.8–5.0 mm; head generally slightly visible from
above; mature color black; antennal club conical with
three straight sutures, rst segment of club longer than
others; disnct median longitudinal ridge located midway
between the base of the eyes and the mouth; punctures
on pronotum somewhat irregular, but generally uniformly
large; margins of pronotum gently, outwardly curved when
viewed from above; declivity convex, steep; vesture
consisng of sparse, nearly scale-like bristles on declivity.
Hylastes porculus, Flight Phenology, Central Massachusetts, 2014.
Hylastes porculus, frons, location of frontal carina.
30
Hylastes tenuis Eichoff
31
Biology
Largely unknown, but likely similar to other members of the
genus.
Northeastern Hosts
Pinus echinata (shortleaf pine), Pinus resinosa (red pine),
Pinus rigida (pitch pine), Pinus strobus (eastern white pine),
Pinus sylvestris (Scots pine), Pinus virginiana (Virginia pine)
Gallery
Unknown, but likely similar to those of other members of
the tribe (Hylurgops, Hylastes).
Identication
Easily separated from H. porculus by the absence of a
median ridge on the lower frons and by its smaller size.
Disnguished from H. opacus by the shape of the pronotum,
which is very gently and evenly rounded, somemes
appearing parallel sided when viewed from above.
Length 2.0–2.5 mm; head generally slightly visible from
above; mature body color dark brown to nearly black;
antennal club conical with three straight sutures, rst
segment of club longer than others; pronotum slightly
elongate, about 1.2 mes longer than wide, widest at base
and gently, evenly rounded; declivity evenly convex and
steep; vesture of short, erect hair-like bristles, somewhat
longer and more abundant on declivity.
Hylastes tenuis, Flight Phenology, Long Island, New York, 2017.
Hylastes tenuis, frons, frontal carina absent.
32
Hylurgops pinifex (Fitch)
33
Biology
Overwintering occurs in the late larval and adult stages.
Typically constructs tunnels in stumps and roots at or just
below ground level and rarely in the bole.
Northeastern Hosts
Pinus banksiana (jack pine), Pinus resinosa (red pine), Pinus
strobus (eastern white pine), Pinus virginiana (Virginia
pine), Larix laricina (tamarack), Picea glauca (white spruce)
Gallery
Simple or branching egg tunnels in phloem ssues, which
may slightly engrave the xylem. Eggs are placed in niches
and larvae mine phloem ssues aimlessly. Larval tunnels
can usually be seen in the phloem when the bark is peeled
back. The random larval tunneling eventually renders the
gallery paerns indisnguishable.
Identication
This genus is very closely related to Hylastes and can be
disnguished by the presence of equal numbers of large
and small punctures on the top of the pronotum. Compared
to the similarly sized Hylastes porculus, this species is much
stouter, with a noceable constricon in the front poron
of the pronotum.
Length 3.7–5.2 mm; stout; head generally visible from
above; mature color reddish brown; antennal club conical
with three straight sutures, rst segment of club longer than
others; punctures on pronotum consisng of two disnct
sizes, evenly distributed; pronotum strongly constricted
toward the front; vesture of short, oval scales restricted
to posterior half of the body and sparse bristles in rows on
declivity.
Hylurgops pinifex, Flight Phenology, Central Massachusetts, 2014.
Parental (red) and larval galleries of H. pinifex.
34
Other Species in Northeastern Pines Not Treated in This Guide
Other common species of bark beetles inhabiting northeastern pines that are not treated in this guide. Scale bars represent 0.5 mm.
(A) Ambrosiophilus atratus, (B) Crypturgus alutaceus, (C) Dryocoetes autographus, (D) Dryocoetes affaber, (E) Euwallacea validus,
(F) Gnathotrichus materiarius, (G) Pityogenes hopkinsi, (H) Pityophthorus confusus, (I) Pityophthorus pulicarius, (J) Tomicus piniperda,
(K) Trypodendron lineatum, (L) Xyleborinus saxesenii, (M) Xyleborus pubescens, (N) Xylosandrus germanus.
A B C D
E F G
H I
K
J
L M N
35
Glossary of Technical Terms
Abdomen—the third or posterior, major division of the insect body, consisng primively of 11 segments, but
normally with 9 or 10 apparent segments and bearing no funconal legs in the adult stage
Antennal club—the more or less enlarged distal arcles of a clubbed antenna
Anterior—in front; before
Apex—end of any structure distal to the base
Bisinuate—with two sinuaons
Brood—all the individuals that hatch at about the same me from eggs laid by one series of parents and that
normally mature at about the same me
Callow—condion of the adult shortly aer transforming from pupa to adult when its cucle is not fully hardened or
fully mature in color
Cambium—in the stems and roots of vascular plants, a layer of cells lying between the xylem and phloem
Carina—an elevated ridge or keel, not necessarily high or acute
Clypeus—that part of the insect head below the frons, to which the labrum is aached anteriorly
Coxa—the basal segment of the leg, by means of which it is arculated to the body
Declivity—downward sloping poron of a parcular structure (for example, elytral declivity is the apical downward
sloping poron of the elytra)
Dencle—a small tooth
Distal—near or toward the free end of any appendage; that part of a segment farthest from the body
Dorsal—on or of the funconally upper surface
Elytra—the leathery forewing of beetles (Coleoptera) that serves as a covering for the hind wings, commonly meeng
opposite elytron in a straight line down the middle of the dorsum in repose (singular = elytron)
Epicranium—the upper part of the head from the frons to the neck that includes frons, vertex, and genae
Epistoma—the oral margin or sclerite directly behind the labrum
Frass—solid larval insect excrement; plant fragments made by wood-boring insects, usually mixed with excrement
Frons—the upper anterior poron of the head capsule, usually a disnct sclerite between the epicranium and clypeus
Funicle—that part of the antenna comprising all the segments between the scape and the club
Gallery—mine, tunnel, or burrow visible beneath the epidermis of plant ssue, made by a larva
Genae—cheeks; the part of the cranium on each side below the eye
Granule—a small grain or a minute grain-like elevaon
Instar—stage between molts in the nymph or larva, numbered to designate the various stages (for example, the rst
instar is the stage between the egg and rst molt)
Integument—the outer layer of the exoskeleton of an insect
Labrum—the upper lip, abung the clypeus in front of the mouth
Lateral—relang, pertaining, or aached to the side
Margin—the part of a surface along the edge
Mesal—pertaining to, situated on, or in the midline of the body
Obliquely truncate—cut o slanngly (any direcon between perpendicular and horizontal) at the p
Occiput—the posterior part the epicranium between the vertex and the neck
Phloem—plant ssue made of various cell types that transports dissolved organic and inorganic materials over long
distances within vascular plants; disnguished from xylem by the general absence of thickened cells and by the
presence of cells containing areas resembling a sieve
(connued on next page)
36
Glossary of Technical Terms (continued)
Pitch tube—conical or globular erupons of pitch from the bark of a tree; created by the tree as a defensive response
to aacking beetles in an eort to eject the beetle from its bore hole
Posterior—hinder or hindmost, opposed to anterior
Procurved—curved forward
Pronotum—the upper and dorsal part of the prothorax
Prothorax—the middle segment of an insect body, between the head and the abdomen
Punctaon—pits or depressions of variable size in the cucle
Recurved—curved backward
Scape—the rst or basal segment of the antenna
Sclerite—any plate of the body wall bounded by membrane or sutures
Setae—hair like projecons of the cucle
Sinuate—cut into sinuses; wavy, oen applying specically to edges and margins
Spine—a more or less thorn-like process or outgrowth of the cucle not separated from it by a joint
Suture—groove marking the line of fusion of two formerly disnct plates
Thorax—middle poron of the body between the head and abdomen, consisng of three segments (prothorax,
mesothorax, and metathorax), each of which usually bears a pair of arculated legs
Tubercle—a small, knob-like or rounded protuberance
Ventral—pertaining to the under surface of a structure or body
Vertex—the top of the head between the eyes, frons, and occiput
Vesture—the general surface covering comprised of cucular projecons (for example, setae, scales)
Xylem—plant ssue consisng of various cell types that transports water and dissolved substances to the leaves,
possessing vercal systems of dead cells with thick, lignied walls; the wood of trees and shrubs
Selected Bibliography
Bright, D.E. 1976. The bark beetles of Canada and Alaska. The insects and arachnids of Canada, part 2. Biosystemacs
Research Instute, Research Branch, Canada Department of Agriculture Publicaon 1576. 241 p.
Coulson, R.N.; Klepzig, K.D. 2011. Southern pine beetle II. Gen. Tech. Rep. SRS–140. Asheville, NC: U.S. Department of
Agriculture Forest Service, Southern Research Staon. 512 p.
Dodds, K.J.; Aoki, C.F.; Arango-Velez, A.; Cancelliere, J.; D’Amato, A.W.; DiGirolomo, M.F.; Rabaglia, R.J. 2018. Expansion of
southern pine beetle into northeastern forests: management and impact of a primary bark beetle in a new region.
Journal of Forestry. 116(2): 178–191.
Torre-Bueno, J.R. 1989. The Torre-Bueno Glossary of Entomology. Revised Edion. New York, N.Y. New York Entomological
Society in cooperaon with the American Museum of Natural History. 521 p.
Wood, S.L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolydae), a Taxonomic
Monograph. Great Basin Naturalist Memoirs. 6: 1356 p.
37
Photo Credits
All images by Marc DiGirolomo, USDA Forest Service, except the following:
Cover photo: The underside of bark peeled from a pine tree killed by the southern pine beetle (Dendroctonus
frontalis), showing the typical serpenne feeding galleries. (Courtesy photo by W.H. Benne, USDA Forest Service,
Bugwood.org)
Page 3: Dendroctonus frontalis-infested pine tree. (Erich G. Vallery, USDA Forest Service - SRS-4552, Bugwood.org)
Page 13: Winding, S-shaped parental galleries of Dendroctonus frontalis. (Ronald F. Billings, Texas A&M Forest Service,
Bugwood.org)
Page 15: Egg galleries and gregarious larval feeding area of D. terebrans. (Ronald F. Billings, Texas A&M Forest Service,
Bugwood.org)
Page 17: Irregular cave style (le) and vercal linear style (right) egg galleries of D. valens. (Le to right: Ladd
Livingston, Idaho Department of Lands, Bugwood.org; Kenneth E. Gibson, USDA Forest Service, Bugwood.org)
Page 21: X-shaped parental galleries and larval feeding tunnels of I. calligraphus. (Ronald F. Billings, Texas A&M Forest
Service, Bugwood.org)
Page 23: X- and Y-shaped parental galleries of I. grandicollis. (Jerey Eickwort, FL Department of Agriculture and
Consumer Services, Bugwood.org)
Page 25: Y-shaped parental galleries and larval tunneling of I. pini. (David McComb, USDA Forest Service,
Bugwood.org)
Page 35: Parental (red) and larval galleries of H. pinifex. (From Mercado-Vélez, J.; Negrón, J.F. 2014. Revision of the
new world species of Hylurgops LeConte, 1876 with the descripon of a new genus in the Hylasni (Coleoptera:
Scolynae) and comments on some Palearcc species. Zootaxa. 3785(3): 301–342.)
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
After more than a decade of damage in pitch pine forests of New Jersey, an unprecedented range expansion of southern pine beetle (SPB), Dendroctonus frontalis, has recently occurred with populations established or detected in parts of the northeastern United States. Widespread tree mortality in pitch pine stands has occurred on Long Island, New York, an area previously free of SPB. Tree mortality has also been documented in several small pine stands in Connecticut. Trapping surveys have detected SPB farther north than it had previously been known to exist, with positive trap catches in Connecticut, Massachusetts, and Rhode Island. Integrated pest management plans that consist of preventative silvicultural treatments, landscape prioritization, detection and monitoring, and direct control provide the best opportunity to reduce the effects of SPB in northeastern US pine ecosystems. Most hard pine species present in the region are at risk to SPB, but less is known about white pine susceptibility. Unmanaged pine barrens are a particular concern, as they provide stand conditions conducive to SPB outbreaks. Infestation suppression implementing cut-and-leave tactics has been used in some areas of Long Island and will continue to be the primary management tool to limit damage from SPB.
The bark beetles of Canada and Alaska. The insects and arachnids of Canada, part 2. Biosystematics Research Institute, Research Branch, Canada Department of Agriculture Publication 1576
  • D E Bright
Bright, D.E. 1976. The bark beetles of Canada and Alaska. The insects and arachnids of Canada, part 2. Biosystematics Research Institute, Research Branch, Canada Department of Agriculture Publication 1576. 241 p.
Southern pine beetle II
  • R N Coulson
  • K D Klepzig
Coulson, R.N.; Klepzig, K.D. 2011. Southern pine beetle II. Gen. Tech. Rep. SRS-140. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 512 p.
The Torre-Bueno Glossary of Entomology
  • J R Torre-Bueno
Torre-Bueno, J.R. 1989. The Torre-Bueno Glossary of Entomology. Revised Edition. New York, N.Y. New York Entomological Society in cooperation with the American Museum of Natural History. 521 p.
USDA Forest Service, except the following: Cover photo: The underside of bark peeled from a pine tree killed by the southern pine beetle (Dendroctonus frontalis), showing the typical serpentine feeding galleries
  • S L Wood
Wood, S.L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae), a Taxonomic Monograph. Great Basin Naturalist Memoirs. 6: 1356 p. Photo Credits All images by Marc DiGirolomo, USDA Forest Service, except the following: Cover photo: The underside of bark peeled from a pine tree killed by the southern pine beetle (Dendroctonus frontalis), showing the typical serpentine feeding galleries. (Courtesy photo by W.H. Bennett, USDA Forest Service, Bugwood.org) Page 3: Dendroctonus frontalis-infested pine tree. (Erich G. Vallery, USDA Forest Service -SRS-4552, Bugwood.org) Page 13: Winding, S-shaped parental galleries of Dendroctonus frontalis. (Ronald F. Billings, Texas A&M Forest Service, Bugwood.org) Page 15: Egg galleries and gregarious larval feeding area of D. terebrans. (Ronald F. Billings, Texas A&M Forest Service, Bugwood.org) Page 17: Irregular cave style (left) and vertical linear style (right) egg galleries of D. valens. (Left to right: Ladd Livingston, Idaho Department of Lands, Bugwood.org;