(excerpt)
The oak twig pruner is a cerambycid of minor economic importance which is generally common through most of eastern North America. The adult beetles oviposit on living twigs of oak and other hardwoods, and the larvae bore within the twig, subsequently pruning it from the tree. Haldeman (1847) identified this borer as Elaphidion villosus (Fabricius), a species later placed in the genus Elaphidionoides by Linsley (1963). This identification has been accepted and followed by Baker (1972), Craighead (1923, 1950), Duffy (1960), Knull (1946). Linsley (1963), and many other authors

Gosling, D. C. L

English

Valparaiso University

The Great Lakes Entomologist Volume 14 Number 4 - Winter 1981 Number 4 - Winter 1981 Article 3 December 1981 Correct Identity of the Oak Twig Pruner (Coleoptera: Cerambycidae) D. C. L. Gosling Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Gosling, D. C. L. 1981. "Correct Identity of the Oak Twig Pruner (Coleoptera: Cerambycidae)," The Great Lakes Entomologist, vol 14 (4) Available at: https://scholar.valpo.edu/tgle/vol14/iss4/3 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1981 THE GREAT LAKES ENTOMOLOGIST 179 CORRECT IDENTITY OF THE OAK TWIG PRUNER (COLEOPTERA: CERAMBYCIDAE) D. C. L. Gosling 1 The oak twig pruner is a cerambycid of minor economic importance which is generally common through most of eastern North America. The adult beetles oviposit on living twigs of oak and other hardwoods, and the larvae bore within the twig, subsequently pruning it from the tree. Haldeman (1847) identified this borer as Elaphidion villosus (Fabricius), a species later placed in the genus Elaphidionoides by Linsley (1963). This identification has been accepted and followed by Baker (1972), Craighead (1923, 1950), Duffy (1960), Knull (1946). Linsley (1963), and many other authors. A sibling species, Elaphidionoides parallelus (Newman), has frequently been confused with dllosus, and was for a time regarded as the same species. The difficulty in distinguish­ing adults of the two species created a likely situation for error in observations of their biology. but this possibility seems to have received little consideration. The habits of parallelus have simply been described as similar to those of villosus (Knull 1946, Linsley 1963). and parallelus has been widely ignored by authors dealing with forest insect pests. Craighead (1923, p. 70) had a clue to the possible confusion when he observed that the beetle he considered to be viltosus "is sometimes reared from branches which are dead, and in this case does not girdle them. This may be a different species, as some of the larvae show variations from the form described." He did not distinguish the habits or larva of paraUelus, although what he did describe now seems to refer to that species. My recent ecological study of Cerambycidae in southwestern Michigan (Gosling 1981) provided an opportunity to observe both species over a period of six years. I have previous· ly described the habits of parallelus and characters useful in identifying the adults (Gosling 1978). but at that time I had not yet observed the larval activities of villosus. Subsequent success in rearing villosus from several hostplants has helped to clarify the identity of the twig pruner and relationships between the species. The study was conducted from 1976 to 1981 in an 80-ha woodland near Tamarack Lake in St. Joseph County, Michigan. As part of a rearing program, host materials were gathered in the study area and enclosed in screened cages. Twigs infested by the twig pruner can be easily identified and 638 were collected in this manner, plus 55 twigs from another woodland nearby. All of the 280 adult beetles subsequently reared from these twigs were found to be parallelus. Thirty-seven adults of villosus were reared from other host materials. These included branches of TWa americana L., Acer rubrum L., and Cercis canadensis L.; a stem of Toxicodendron radicans (L.) Kuntze; and bolts of Carya glabra (Miller) Sweet. All of these hostplants were dead at the time of oviposition. The branches were 1-3 m d and the Carya bolts were 7 cm d and larger. Adult beetles were also beaten from dead branches of Quercus velutina Lamarck and TWa americana, and collected from a bolt of Carpinus caroliniana Walter. In all cases the adult was reared from or associated with host material which was recently dead, and generally much larger than the twigs from which paraUelus adults were obtained. These observations sh w that paralle/us, not villosus, is the borer which regularly attacks small, living twigs of oak and other hardwoods in southwestern Michigan. E. villosus adults oviposit in branches which are recently dead and usually larger in diameter. There is no reason to believe the host selection behavior of these species in the study ar a is different from that elsewhere in their ranges. The identification of villosus as a twig pruner, then, is not correct. Other differences in the behavior of these species have been noted. E. parallelus adults J 69063 Wallowa Road. White Pigeon, MI 49099. 1Gosling: Correct Identity of the Oak Twig Pruner (Coleoptera: CerambycidaePublished by ValpoScholar, 1981180 THE GREAT LAKES ENTOMOLOGIST VoL 14, No.4 show an overwhelming preference for Quercus velutina and Q. rubra L. as hostplants, and only rarely attack other species of Quercus and Carya. E. vil/osus seems much more cosmo­politan in its host selection, and most of the adults were reared from TWa and Carya. There is also a difference in their adult activity periods. Adults of parallelus in southwestern Michigan emerge in late May and early June, while vii/osus adults emerge later, from mid- through late June. Flight activity of parallelus extends from late May through early July, and that of vil/osus from mid-June through july. A similar pattern in activity periods of these species has been observed in material collected in Connecticut by M. E. Montgomery (pers. comm).2 The published accounts of twig pruner activity cited above refer to parall lus and the larval behavior of villosus has not been described. A typical villosus larva feeds beneath the bark of the branch, excavating a broad, irregularly shaped chamber with an overaillength of 100-150 mm and 5-20 mm wide. Its boring removes the inner bark and cuts 2-3 mm into the sapwood, leaving a paper-thin layer of outer bark covering the chamber. If the larva is boring in a small branch it will usually pupate between plugs of shredded wood in a narrow extension of the chamber. In a larger branch the larva extends a narrow, oval gallery to the center of the branch and continues down the center for as much as 120 mm. Pupation then takes place between shredded-wood plugs near the end of this gallery. In either case the emerging adult exits through a hole in the bark cut previously and used for expelling frass. The life-cycle requires two years to complete in southwestern Michigan, and adults are usually present only in odd-number years. The larval behavior of villosus is similar to that of parallelus in several respects. E. parallelus larvae often excavate a smaller version of the feeding chamber before starting their principal gallery in the main stem of twig. Both species expel frass during larval feeding, and both exit as adults through pre-existing holes. If the size of the host material permits, both borers excavate a similar gallery down the center of the twig or branch and pupate at the end of it between plugs of shredded wood. The principal differences are that parallelus larvae begin feeding in a living twig, feed mostly by narrow galleries extended in the sapwood, and make their characteristic pruning cut which often severs the twig from the host tree. E. vil/osus larvae feed in recently dead hostplants, in a broad chamber beneath the bark, and do not make a pruning cut. These differences in larval feeding behavior seem to be adaptations to the differences in size of host material utilized and probably in its condition as well. The mating behavior ofthese beetles has only been observed in cages, where adults copulate shortly after emerg­ence. It is not known if differences in host selection serve to isolate adults while mating, but their difference in emergence period undoubtedly provides effective temporal isolation between these sympatric and presumably closely related species. LITERATURE CITED Baker, W. L. 1972. Eastern forest insects. USDA Forest Service, Misc. Publ. 1175. Craighead, F. C. 1923. North American cerambycid larvae. Dom. Canada Agric. Bull. 27. ___. 1950. Insect enemies of eastern forests. USDA Misc. Pub!. 657. Duffy, E. A. J. 1960. A monograph of the immature stages of Neotropical timber beetles (Cerambycidae). British Mus. (Nat. Hist.), London. Gosling, D. C. L. 1978. Observations on the biology fthe oak twig pruner, Elaphidionoides parallelus, (Coloeoptera: Cerambycidae) in Michigan. Great Lakes Entomol. 11:1-10. 1981. Ecology of the Cerambycidae in a southwestern Michigan woodland. Ph.D. dissert., Univ. Michigan, Ann Arbor. Haldeman, S. S. 1847. Materials towards a history of the Coleoptera Longicornia of the United States. Trans. Amer. Phil. Soc. 10:27-66. Knull, J. N. 1946. The long-homed beetles of Ohio (Coleoptera: Cerambycidae). Ohio BioI. Surv. Bull. 39:133-354. Linsley, E. G. 1963 The Cerambycidae of North America, Part IV, Taxonomy and clas­sification of the subfamily Cerambycinae, tribes Elaphidionini through Rhinotragini. Univ. California Pub!. Entomol. 21. 2 Northeastern Forest Experiment Station, Hamden. CT 06514. 2The Great Lakes Entomologist, Vol. 14, No. 4 [1981], Art. 3https://scholar.valpo.edu/tgle/vol14/iss4/3

Correct Identity of the Oak Twig Pruner (Coleoptera: Cerambycidae)

ValpoScholar

The Great Lakes Entomologist 
Volume 14 
Number 4 - Winter 1981 Number 4 - Winter 
1981 
Article 3 
December 1981 
Correct Identity of the Oak Twig Pruner (Coleoptera: 
Cerambycidae) 
D. C. L. Gosling 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Gosling, D. C. L. 1981. "Correct Identity of the Oak Twig Pruner (Coleoptera: Cerambycidae)," The Great 
Lakes Entomologist, vol 14 (4) 
Available at: https://scholar.valpo.edu/tgle/vol14/iss4/3 
This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. 
It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. 
For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 
1981 THE GREAT LAKES ENTOMOLOGIST 179 
CORRECT IDENTITY OF THE OAK TWIG PRUNER 
(COLEOPTERA: CERAMBYCIDAE) 
D. C. L. Gosling 1 
The oak twig pruner is a cerambycid of minor economic importance which is generally 
common through most of eastern North America. The adult beetles oviposit on living twigs 
of oak 
and 
other hardwoods, and the larvae bore within the twig, subsequently pruning it 
from the tree. Haldeman (1847) identified this borer as Elaphidion villosus (Fabricius), a 
species later placed in the genus Elaphidionoides by Linsley (1963). This identification has 
been accepted and followed by Baker (1972), Craighead (1923, 1950), Duffy (1960), Knull 
(1946). Linsley (1963), and many other authors. 
A sibling species, Elaphidionoides parallelus (Newman), has frequently been confused 
with dllosus, and was for a time regarded as the same species. The difficulty in distinguish­
ing adults of the two species created a likely situation for error in observations of their 
biology. but this possibility seems to have received little consideration. The habits of 
parallelus have simply been described as similar to those of villosus (Knull 1946, Linsley 
1963). and parallelus has been widely ignored by authors dealing with forest insect pests. 
Craighead (1923, p. 70) had a clue to the possible confusion when he observed that the 
beetle he considered to be viltosus "is sometimes reared from branches which are dead, and 
in this case does not girdle them. This may be a different species, as some of the larvae show 
variations from the form described." He did not distinguish the habits or larva of paraUelus, 
although what he did describe now seems to refer to that species. 
My recent ecological study of Cerambycidae in southwestern Michigan (Gosling 1981) 
provided an opportunity to observe both species over a period of six years. I have previous· 
ly described the habits of parallelus and characters useful in identifying the adults (Gosling 
1978). but at that time I had not yet observed the larval activities of villosus. Subsequent 
success in rearing villosus from several hostplants has helped to clarify the identity of the 
twig pruner and relationships between the species. 
The 
study was conducted from 
1976 to 1981 in an 80-ha woodland near Tamarack Lake in 
St. Joseph County, Michigan. As part of a rearing program, host materials were gathered in 
the study area and enclosed in screened cages. Twigs infested by the twig pruner can be 
easily identified and 638 were collected in this manner, plus 55 twigs from another woodland 
nearby. All of the 280 adult beetles subsequently reared from these twigs were found to be 
parallelus. 
Thirty-seven adults of villosus were reared from other host materials. These included 
branches of TWa americana L., Acer rubrum L., and Cercis canadensis L.; a stem of 
Toxicodendron radicans (L.) Kuntze; and bolts of Carya glabra (Miller) Sweet. All of these 
hostplants were dead at the time of oviposition. The branches were 1-3 m d and the Carya 
bolts were 7 cm d and larger. Adult beetles were also beaten from dead branches of Quercus 
velutina Lamarck and TWa americana, and collected from a bolt of Carpinus caroliniana 
Walter. In all cases the adult was reared from or associated with host material which was 
recently dead, and generally much larger than the twigs from which paraUelus adults were 
obtained. 
These observations sh w that paralle/us, not villosus, is the borer which regularly attacks 
small, living twigs of oak and other hardwoods in southwestern Michigan. E. villosus adults 
oviposit in branches which are recently dead and usually larger in diameter. There is no 
reason to believe the host selection behavior of these species in the study ar a is different 
from that elsewhere in their ranges. The identification of villosus as a twig pruner, then, is 
not 
correct. Other 
differences 
in the behavior of these species have been noted. E. parallelus adults 
J 69063 Wallowa Road. White Pigeon, MI 49099. 
1
Gosling: Correct Identity of the Oak Twig Pruner (Coleoptera: Cerambycidae
Published by ValpoScholar, 1981
180 THE GREAT LAKES ENTOMOLOGIST VoL 14, No.4 
show 
an overwhelming preference for 
Quercus velutina and Q. rubra L. as hostplants, and 
only rarely attack other species of Quercus and Carya. E. vil/osus seems much more cosmo­
politan in its host selection, and most of the adults were reared from TWa and Carya. There 
is also a difference in their adult activity periods. Adults of parallelus in southwestern 
Michigan emerge in late May and early June, while vii/osus adults emerge later, from 
mid- through late June. Flight activity of parallelus extends from late May through early 
July, and that of vil/osus from mid-June through july. A similar pattern in activity periods of 
these species has been observed in material collected in Connecticut by M. E. Montgomery 
(pers. comm).2 
The published accounts of twig pruner activity cited above refer to parall lus and the 
larval behavior of villosus has not been described. A typical villosus larva feeds beneath the 
bark of 
the branch, excavating a broad, irregularly shaped chamber with an overaillength 
of 
100-150 mm and 5-20 mm wide. Its boring removes the inner bark and cuts 2-3 mm into the 
sapwood, leaving a paper-thin layer of outer bark covering the chamber. If the larva is 
boring in a small branch it will usually pupate between plugs of shredded wood in a narrow 
extension of the chamber. In a larger branch the larva extends a narrow, oval gallery to the 
center of the 
branch and continues down 
the center for as much as 120 mm. Pupation then 
takes place between shredded-wood plugs near the end of this gallery. In either case the 
emerging adult exits through a hole in the bark cut previously and used for expelling frass. 
The 
life-cycle requires two years 
to complete in southwestern Michigan, and adults are 
usually present only in odd-number years. 
The 
larval behavior 
of villosus is similar to that of parallelus in several respects. E. 
parallelus larvae often excavate a smaller version of the feeding chamber before starting 
their principal gallery in the main stem of twig. Both species expel frass during larval 
feeding, and both exit as adults through pre-existing holes. If the size of the host material 
permits, both borers excavate a similar gallery down the center of the twig or branch and 
pupate at the end of it between plugs of shredded wood. The principal differences are that 
parallelus larvae begin feeding in a living twig, feed mostly by narrow galleries extended in 
the 
sapwood, and make their characteristic pruning cut which often severs the twig from the host 
tree. 
E. vil/osus larvae feed in recently dead hostplants, in a broad chamber beneath the 
bark, and do not make a pruning cut. 
These 
differences 
in larval feeding behavior seem to be adaptations to the differences in 
size of host material utilized and probably in its condition as well. The mating behavior of
these 
beetles has only been observed in cages, where adults copulate shortly after emerg­
ence. 
It is not known if differences in host selection serve to isolate adults while mating, but 
their difference in emergence period undoubtedly provides effective temporal isolation 
between these sympatric and presumably closely related species. 
LITERATURE CITED 
Baker, 
W. 
L. 1972. Eastern forest insects. USDA Forest Service, Misc. Publ. 1175. 

Craighead, F. C. 1923. North American cerambycid larvae. Dom. Canada Agric. Bull. 27. 

___
. 
1950. Insect enemies of eastern forests. USDA Misc. Pub!. 657. 

Duffy, E. A. J. 1960. A monograph of the immature stages of Neotropical timber beetles 

(Cerambycidae). British Mus. (Nat. Hist.), London. 
Gosling, D. C. L. 1978. Observations on the biology fthe oak twig pruner, Elaphidionoides 
parallelus, (Coloeoptera: Cerambycidae) in Michigan. Great Lakes Entomol. 11:1-10. 
1981. 
Ecology 
of the Cerambycidae in a southwestern Michigan woodland. Ph.D. 
dissert., Univ. Michigan, Ann Arbor. 
Haldeman, S. S. 1847. Materials towards a history of the Coleoptera Longicornia of the 
United States. Trans. Amer. Phil. Soc. 10:27-66. 
Knull, J. N. 1946. The long-homed beetles of Ohio (Coleoptera: Cerambycidae). Ohio BioI. 
Surv. Bull. 39:133-354. 
Linsley, E. G. 1963 The Cerambycidae of North America, Part IV, Taxonomy and clas­
sification of the subfamily Cerambycinae, tribes Elaphidionini through Rhinotragini. 
Univ. California Pub!. Entomol. 21. 
2 Northeastern Forest Experiment Station, Hamden. CT 06514. 
2
The Great Lakes Entomologist, Vol. 14, No. 4 [1981], Art. 3
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Correct Identity of the Oak Twig Pruner (Coleoptera: Cerambycidae)

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