Eastern white pine and Scotch pine stumps with living branches were unattractive to pales weevil for breeding. When feasible, leaving a few lower branches on Christmas tree stumps during harvest should prevent weevil buildup

Corneil, Jeffrey A

Wilson, Louis F

English

Jeffrey A Corneil

Louis F Wilson

Crossref

Live Branches on Pine Stumps Deter Pales Weevil Breeding in Michigan (Coleoptera: Curculionidae)

ValpoScholar

The Great Lakes Entomologist 
Volume 17 
Number 4 - Winter 1984 Number 4 - Winter 
1984 
Article 9 
December 1984 
Live Branches on Pine Stumps Deter Pales Weevil Breeding in 
Michigan (Coleoptera: Curculionidae) 
Jeffrey A. Corneil 
Oregon Department of Forestry 
Louis F. Wilson 
USDA Forest Service 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Corneil, Jeffrey A. and Wilson, Louis F. 1984. "Live Branches on Pine Stumps Deter Pales Weevil Breeding 
in Michigan (Coleoptera: Curculionidae)," The Great Lakes Entomologist, vol 17 (4) 
Available at: https://scholar.valpo.edu/tgle/vol17/iss4/9 
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. 
1984 THE GREAT LAKES ENTOMOLOGIST 229 
LIVE BRANCHES ON PINE STUMPS DETER PALES WEEVIL 

BREEDING IN MICHIGAN (COLEOPTERA: CURCULIONIDAE) 

Jeffrey A. CorneiI1 and Louis F. Wilson2 
ABSTRACT 
Eastern white pine and Scotch pine stumps with living branches were unattractive to 
pales weevil for breeding. When feasible, leaving a few lower branches on Christmas tree 
stumps during harvest should prevent weevil buildup. 
Pine stumps are the major breeding material for the pales weevil, Hylobius pales 
(Herbst) (Pierson 1921, Finnegan 1959). While studying the pales weevil in Christmas 
tree plantations in Michigan (Corneil and Wilson, 1984), we noticed that stumps left with 
a whorl of living branches were not used for breeding. In Wiseo sin, however, Goyer et 
al. (1971) reported that pales weevils attacked living Scotch pine (Pinus sylvestris L,) 
trees and stumps left with a living whorl of branches. Our study was made in two 
Michigan Christmas tree plantations on Scotch pine and eastern white pine, P. strobus L" 
to determine if pine stumps with a living whorl of branches intact would be used by pales 
weevil for breeding. 
METHODS AND MATERIALS 
A preliminary test was made in July 1979 on 30 Scotch pine Christmas trees in a 
plantation in Tuscola County, Michigan (TIlN, R8E, S 1). Fifty percent of the trees were 
cut so the stumps were left with a whorl of live branches; the other 50% were cut leaving 
no 
branches. 
All stumps were dug up in September, examined for weevil injury, and then 
recorded as infested or not. 
Encouraging results of the first trial prompted a second test in 1980. In July, 30 more 
Scotch pine and 30 eastern white pine trees were selected in another Christmas tree 
plantation in Genesee County, Michigan (T9N, R5E, S22). Fifty percent of the trees of 
each species were cut and left with branches as before; the remaining 50% were cut 
leaving no branches. In September, seven stumps were selected randomly from each 
species and treatment group, dug up, and taken to the laboratory for dissection. The bark 
was 
removed from each stump, and the number of pales weevil larvae, pupae, adults, and 
empty pupal cells were counted to determine the level 
of attack. 
RESULTS AND DISCUSSION 
In 
the 1979 preliminary test, only Scotch pine stumps left with branches intact were 
uninfested by the pales weevil. All stumps with branches removed, however. were in­
fested. Similarly in the 1980 test, eastern white pine and Scotch pine stumps with live 
branches did not have any sign 
of the pales weevil or its injury, nor was there apparent 
feeding nor ovipos tion. All but one stump without branches were infested (Table 1). The 
uninfested stump was partially rotted and attacked only by the northern pine weevil, 
IOregon Department of Forestry, Prineville, OR 97754. 

2North Central Forest Experiment Station, USDA Forest Service, East Lansing, MI48823. 

1
Corneil and Wilson: Live Branches on Pine Stumps Deter Pales Weevil Breeding in Michi
Published by ValpoScholar, 1984
230 THE GREAT LAKES ENTOMOLOGIST Vol. 17, No.4 
Table 1. Number of pales weevil attacks on eastern white pine and Scotch pine stumps, 
with and without living branches, in the 1980 test. 
Stumps with branches Stumps without branches 
Sample 
number E. white pine Scotch pine E. white pine Scotch pine 
1 0 31 9 
2 0 0 21 77 
3 0 32 38 
4 0 0 19 29 
5 0 0 33 Ob 
6 0 0 22 50 
7 0 0 8 6 
Total 0 0 166 209 
a Branches on these stumps died during the summer. White pine and Scotch pine stumps 

had 14 and 74 attacks, respectively. 

b Stump was partially rotted and contained only Pissodes approximatus. 

Pissodes approximatus Hopkins. Though this sample was small, Scotch pine stumps 
averaged 34.8 attacks and were apparently preferred over eastern white pine, which 
averaged 23.7 attacks. 
Apparently, as long as branches left on the stumps remained alive, the stumps were 
unattractive to the weevil for breeding, unlike the situation reported by Goyer et al. (1971) 
in Wisconsin. When branches died on two stumps in our test, weevils readily attacked 
them; one white pine had 14 and one Scotch pine had 74 attacks (Table 1). These findings 
were further supported by the observations of some Michigan Christmas tree growers that 
used tip-up stump culture, in which a lower branch is left on the stump and later shaped 
into a Christmas tree. When growers stopped using stump culture and cut their trees 
normally, problems with the pales weevil began again. 
Goyer et al. (1971) also reported flagging of living Scotch pine trees and tree mortality 
from larval pales weevil feeding in the roots. Examination of six injured Christmas tree 
plantations showed flagging, but it was always associated with adult feeding and not 
larval injury. No whole-tree mortality was observed. 
In a heavily infested Christmas tree plantation, we examined several living Scotch pines 
for root feeding by the weevil and found none. The reason for these differences between 
Wisconsin and Michigan Christmas tree plantings is unknown. Perhaps the trees must be 
heavily stressed before pales weevils will attack living trees or stumps with live branches. 
Most pales weevil problems in Michigan are in the "thumb" area where soils are better 
than average for Christmas tree growth and vigor, and only branchless stumps are attacked 
there. 
Goyer et al. (1971) were also dealing with a complex of three Hylobius species: pales, 
radicis Buchanan, and rhizophagus Millers. Flagging due to larval feeding is normally 
associated only with H. rh zophagus, but Goyer et al. (1971) noted that 60% of the trees 
with flags were injured only by larval pales weevils. Unless the adults they reared were 
misidentified, this means there is a strain, new species, or perhaps a hybrid weevil that is 
as 
destructive to living trees 
as rhizophagus. We recorded a Hylobius complex on Scotch 
pine in several stands in Michigan but found only radicis and rhizophagus, and only 
where trees were grown for stump culture of Christmas trees but later abandoned (Mosher 
and Wilson 1977). 
In Michigan radicis and rhizophagus have not yet been a problem where pales is 
important. So, until pales weevils take on a new role and attack living trees in Michigan, 
we recommend when practicable leaving a whorl of live branches on stumps until final 
harvest to prevent pales weevil injury. Then destroy the stumps before establishing a new 
plantation. 
2
The Great Lakes Entomologist, Vol. 17, No. 4 [1984], Art. 9
https://scholar.valpo.edu/tgle/vol17/iss4/9
1984 THE GREAT LAKES ENTOMOLOGIST 231 
LITERATURE CITED 
Corneil, J. A. and L. F. Wilson. 1984. Dispersion and seasonal activity of the pales 
weevil, Ilylobius pales (Co]eoptera:Curculionidae), in Michigan Christmas tree planta­
tions. Canadian Entomol. 116:711-717. 
Finnegan, R. J. 1959. The pales weevil, Ilylobius pales (Herbst), in Southern Ontario. 
Canadian Entomol. 91:644-670. 
Goyer, R. A., G. D. Hertel, and D. M. Benjamin. 1971. Branch mortality of Scotch pine 
caused by pales weevil larvae. Amer. Christmas Tree Growers J. 15:33-35. 
Mosher, D. G. and L. F. Wilson. 1977. Scotch pine det rioration in Michigan caused by 
pine root weevil complex. Great Lakes Entomol. 10: 169-172. 
Pierson, H. B. 1921. The life history and control of the pales weevil (Ilylob us pales). 
Harvard For. Bull. 3. 33 p. 
3
Corneil and Wilson: Live Branches on Pine Stumps Deter Pales Weevil Breeding in Michi
Published by ValpoScholar, 1984


Valparaiso University

The Great Lakes Entomologist Volume 17 Number 4 - Winter 1984 Number 4 - Winter 1984 Article 9 December 1984 Live Branches on Pine Stumps Deter Pales Weevil Breeding in Michigan (Coleoptera: Curculionidae) Jeffrey A. Corneil Oregon Department of Forestry Louis F. Wilson USDA Forest Service Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Corneil, Jeffrey A. and Wilson, Louis F. 1984. "Live Branches on Pine Stumps Deter Pales Weevil Breeding in Michigan (Coleoptera: Curculionidae)," The Great Lakes Entomologist, vol 17 (4) Available at: https://scholar.valpo.edu/tgle/vol17/iss4/9 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. 1984 THE GREAT LAKES ENTOMOLOGIST 229 LIVE BRANCHES ON PINE STUMPS DETER PALES WEEVIL BREEDING IN MICHIGAN (COLEOPTERA: CURCULIONIDAE) Jeffrey A. CorneiI1 and Louis F. Wilson2 ABSTRACT Eastern white pine and Scotch pine stumps with living branches were unattractive to pales weevil for breeding. When feasible, leaving a few lower branches on Christmas tree stumps during harvest should prevent weevil buildup. Pine stumps are the major breeding material for the pales weevil, Hylobius pales (Herbst) (Pierson 1921, Finnegan 1959). While studying the pales weevil in Christmas tree plantations in Michigan (Corneil and Wilson, 1984), we noticed that stumps left with a whorl of living branches were not used for breeding. In Wiseo sin, however, Goyer et al. (1971) reported that pales weevils attacked living Scotch pine (Pinus sylvestris L,) trees and stumps left with a living whorl of branches. Our study was made in two Michigan Christmas tree plantations on Scotch pine and eastern white pine, P. strobus L" to determine if pine stumps with a living whorl of branches intact would be used by pales weevil for breeding. METHODS AND MATERIALS A preliminary test was made in July 1979 on 30 Scotch pine Christmas trees in a plantation in Tuscola County, Michigan (TIlN, R8E, S 1). Fifty percent of the trees were cut so the stumps were left with a whorl of live branches; the other 50% were cut leaving no branches. All stumps were dug up in September, examined for weevil injury, and then recorded as infested or not. Encouraging results of the first trial prompted a second test in 1980. In July, 30 more Scotch pine and 30 eastern white pine trees were selected in another Christmas tree plantation in Genesee County, Michigan (T9N, R5E, S22). Fifty percent of the trees of each species were cut and left with branches as before; the remaining 50% were cut leaving no branches. In September, seven stumps were selected randomly from each species and treatment group, dug up, and taken to the laboratory for dissection. The bark was removed from each stump, and the number of pales weevil larvae, pupae, adults, and empty pupal cells were counted to determine the level of attack. RESULTS AND DISCUSSION In the 1979 preliminary test, only Scotch pine stumps left with branches intact were uninfested by the pales weevil. All stumps with branches removed, however. were in­fested. Similarly in the 1980 test, eastern white pine and Scotch pine stumps with live branches did not have any sign of the pales weevil or its injury, nor was there apparent feeding nor ovipos tion. All but one stump without branches were infested (Table 1). The uninfested stump was partially rotted and attacked only by the northern pine weevil, IOregon Department of Forestry, Prineville, OR 97754. 2North Central Forest Experiment Station, USDA Forest Service, East Lansing, MI48823. 1Corneil and Wilson: Live Branches on Pine Stumps Deter Pales Weevil Breeding in MichiPublished by ValpoScholar, 1984230 THE GREAT LAKES ENTOMOLOGIST Vol. 17, No.4 Table 1. Number of pales weevil attacks on eastern white pine and Scotch pine stumps, with and without living branches, in the 1980 test. Stumps with branches Stumps without branches Sample number E. white pine Scotch pine E. white pine Scotch pine 1 0 31 9 2 0 0 21 77 3 0 32 38 4 0 0 19 29 5 0 0 33 Ob 6 0 0 22 50 7 0 0 8 6 Total 0 0 166 209 a Branches on these stumps died during the summer. White pine and Scotch pine stumps had 14 and 74 attacks, respectively. b Stump was partially rotted and contained only Pissodes approximatus. Pissodes approximatus Hopkins. Though this sample was small, Scotch pine stumps averaged 34.8 attacks and were apparently preferred over eastern white pine, which averaged 23.7 attacks. Apparently, as long as branches left on the stumps remained alive, the stumps were unattractive to the weevil for breeding, unlike the situation reported by Goyer et al. (1971) in Wisconsin. When branches died on two stumps in our test, weevils readily attacked them; one white pine had 14 and one Scotch pine had 74 attacks (Table 1). These findings were further supported by the observations of some Michigan Christmas tree growers that used tip-up stump culture, in which a lower branch is left on the stump and later shaped into a Christmas tree. When growers stopped using stump culture and cut their trees normally, problems with the pales weevil began again. Goyer et al. (1971) also reported flagging of living Scotch pine trees and tree mortality from larval pales weevil feeding in the roots. Examination of six injured Christmas tree plantations showed flagging, but it was always associated with adult feeding and not larval injury. No whole-tree mortality was observed. In a heavily infested Christmas tree plantation, we examined several living Scotch pines for root feeding by the weevil and found none. The reason for these differences between Wisconsin and Michigan Christmas tree plantings is unknown. Perhaps the trees must be heavily stressed before pales weevils will attack living trees or stumps with live branches. Most pales weevil problems in Michigan are in the "thumb" area where soils are better than average for Christmas tree growth and vigor, and only branchless stumps are attacked there. Goyer et al. (1971) were also dealing with a complex of three Hylobius species: pales, radicis Buchanan, and rhizophagus Millers. Flagging due to larval feeding is normally associated only with H. rh zophagus, but Goyer et al. (1971) noted that 60% of the trees with flags were injured only by larval pales weevils. Unless the adults they reared were misidentified, this means there is a strain, new species, or perhaps a hybrid weevil that is as destructive to living trees as rhizophagus. We recorded a Hylobius complex on Scotch pine in several stands in Michigan but found only radicis and rhizophagus, and only where trees were grown for stump culture of Christmas trees but later abandoned (Mosher and Wilson 1977). In Michigan radicis and rhizophagus have not yet been a problem where pales is important. So, until pales weevils take on a new role and attack living trees in Michigan, we recommend when practicable leaving a whorl of live branches on stumps until final harvest to prevent pales weevil injury. Then destroy the stumps before establishing a new plantation. 2The Great Lakes Entomologist, Vol. 17, No. 4 [1984], Art. 9https://scholar.valpo.edu/tgle/vol17/iss4/91984 THE GREAT LAKES ENTOMOLOGIST 231 LITERATURE CITED Corneil, J. A. and L. F. Wilson. 1984. Dispersion and seasonal activity of the pales weevil, Ilylobius pales (Co]eoptera:Curculionidae), in Michigan Christmas tree planta­tions. Canadian Entomol. 116:711-717. Finnegan, R. J. 1959. The pales weevil, Ilylobius pales (Herbst), in Southern Ontario. Canadian Entomol. 91:644-670. Goyer, R. A., G. D. Hertel, and D. M. Benjamin. 1971. Branch mortality of Scotch pine caused by pales weevil larvae. Amer. Christmas Tree Growers J. 15:33-35. Mosher, D. G. and L. F. Wilson. 1977. Scotch pine det rioration in Michigan caused by pine root weevil complex. Great Lakes Entomol. 10: 169-172. Pierson, H. B. 1921. The life history and control of the pales weevil (Ilylob us pales). Harvard For. Bull. 3. 33 p. 3Corneil and Wilson: Live Branches on Pine Stumps Deter Pales Weevil Breeding in MichiPublished by ValpoScholar, 1984

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Live Branches on Pine Stumps Deter Pales Weevil Breeding in Michigan (Coleoptera: Curculionidae)

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