Olesicampe benefactor Hinz and the Bavarian strain of Mesoleius tenthredinis Morley, European ichneunionid parasites of the larch sawfly, Pristiphora erichsonii (Hartig), were introduced into northern Minnesota from Manitoba in 1971 and 1972. Both species are now established. There was also natural spread of 0. benefactor into Minnesota from Manitoba releases in 1961 at a point ca. 200 miles northwest of the Minnesota plots

Kulman, H M

Thompson, L. C.

Witter, J. A.

English

Valparaiso University

The Great Lakes Entomologist Volume 7 Number 1 -- Spring 1974 Number 1 -- Spring 1974 Article 6 March 1974 Introduction of Parasites of the Larch Sawfly in Minnesota H M. Kulman University of Minnesota L. C. Thompson University of Minnesota J. A. Witter University of Minnesota Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Kulman, H M.; Thompson, L. C.; and Witter, J. A. 1974. "Introduction of Parasites of the Larch Sawfly in Minnesota," The Great Lakes Entomologist, vol 7 (1) Available at: https://scholar.valpo.edu/tgle/vol7/iss1/6 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. THE GREAT LAKES ENTOMOLOGIST INTRODUCTION OF PARASITES OF THE LARCH SAWFLY IN  MINNESOTA^ H. M. Kulman, L. C. Thompson, and J. A. witter2 Department of Entomology, Fisheries, & Wildlife University of Minnesota, St. Paul, Minnesota 5 5 1 0 1  ABSTRACT Olesicampe benefactor Hinz and the Bavarian strain of Mesoleius tenthredinis Morley, European ichneunionid parasites of the larch sawfly, Pristiphora erichsonii (Hartig), were introduced into northern Minnesota from Manitoba in 1971 and 1972. Both species are now established. There was also natural spread of 0. benefactor into Minnesota from Manitoba releases in 1961 at a point ca. 200 miles northwest of the Minnesota plots. Minnesota has over one-half million acres of commercial forests in the tamarack (Larix laricina) timber type. Although greatly under utilized, it is an important resource reserve for forest industries. The only major pest of tamarack in Minnesota is the larch sawfly, Bistiphora erichsonii (Hartig), a univoltine tenthredinid defoliator. Turnock (1973) describes the larch sawfly outbreaks in central and eastern North America as "permanent types" characterized by severe, widespread and prolonged out- breaks. The parasite fauna is composed of only a few species which have little influence on the populations. Tumock points out that there was a break in this pattern lasting from about 1920 to 1938 when the introduced parasite, Mesoleius tenthredinis Morley, was effective. During this period the population system was of the "temporary type" with widely fluctuating outbreaks of short duration. The demise of the temporary type in the late 1930's was associated with the appearance of resistance in the sawfly to the parasite via egg encapsulation (Muldrew 1953). The resistant strain of the sawfly is now dominant in most of the United States and Canada (Drooz 1973). Since experience with Mesoleius indicated that the permanent type can be replaced by the less destructive temporary type of outbreak pattern, Canadian entomologists sought additional European parasites for release. They succeeded with the introductions of two European ichneumonids, Olesicampe benefactor Hinz and an encapsulation resistant strain of'Mesoleius tenthredinis from Bavaria (Turnock and Muldrew 1971). Since the original and Bavarian strain are indistinguishable in morphology, their successful introduction was authenticated by the relative frequency of effective parasitization by M. tenthredinis. Parasitization increased from less than 10% to 30% and 60% in two different release plots. Olesicampe benefactor was also a successful parasite, attacking over 90% of the sawflies in several release locations. In addition, it has a remarkably good dispersal ability and presently can be found within ca. a 200 mile diameter area centered at  a point 100 miles north of Minnesota on the Manitoba-Ontario border (Muldrew, personal communi- cation). Although it has a highly effective hyperparasite, Mesochorus dimidiatus Hlgr., 0 .  benefactor promises to be an important parasite of the larch sawfly (Twnock and Muldrew 1971). Because of the success of the Manitoba introductions and the successful introduction of Olesicampe benefactor into Nova Scotia, New Brunswick, and Maine (Embree and Underwood 1972), the Minnesota Department of Natural Resources and the University of Minnesota started a program to introduce both 0. benefactor and the Bavarian strain of M. tenthredinis into Minnesota. In addition to the protection of our tamarack resource, the goals of the program are to determine the dispersal of these parasites, their interaction with the existing parasite fauna, and to determine the subsequent response in tamarack growth resulting from anticipated reductions in defoliation. These factors are - l ~ a p e r  No. 8241, Scientific Journal Series, Minnesota Agricultural Experiment Sta- tion, St. Paul, Minnesota. l ~ i t t e r  is now at the School of Natural Resources, University of Michigan, Ann Arbor 48104. 1Kulman et al.: Introduction of Parasites of the Larch Sawfly in MinnesotaPublished by ValpoScholar, 197424 THE GREAT LAKES ENTOMOLOGIST Vol. 7, No. 1 important for future management of sawfly populations and to help develop guidelines for biological control of other sawflies. METHODS About 75,000 late instar larch sawfly larvae were collected from areas in Manitoba known t o  be heavily parasitized by either Olesicarnpe benefactor or Mesoleius tentlzredinis. Larvae were reared in cages with tamarack foliage until cocoons were formed. After storage in sphagnum moss at 1°C, the cocoons were placed in groups of 20 in petri dishes and kept a t  15'C until adult parasites emerged. The parasites of each species were placed in a 1 sq. foot mating cage for 2-4 days and then released in sawfly infested stands in north central Minnesota in 1971 and 1972 (Koochiching, Beltrami, Itasca and Lake of the Woods counties). We used 16 stands of 4 or more acres each, spaced 5 or more miles apart. Four plots received approximately 100 mated 0. benefactor females; 4 plots received approximately 350 mated 0. benefactor females; 4 plots approximately 110 mated M. tentlzredinis females and 4 plots were used as controls. RESULTS AND DISCUSSION Preliminary results from the study plots have shown that: (1) Olesicarnpe benefactor has been established in Minnesota from our releases. In 1972, 3 specimens were reared from 2 of the 4 plots where 100 parasites were released and 25 specimens in 3 of the 4 plots that received 350 parasites. ,On the basis of the size of overwintering cocoons, we anticipate that all four of the 350-parasite release plots will show increases in 1973. (2) The Bavarian strain of Mesoleius tentlzredinis has been established in Minnesota from our releases. Prior to 1972 all plots had less than 10% parasitization by Mesoleius. In 1972, 2 of the 4 release plots showed increases in parasitization from 10 to about 30%. All other 14 plots remained a t  less than 10%. (3) There has been natural spread of Olesicarnpe benefactor into Minnesota from the 1961 releases near Pine Falls Manitoba ca. 200 miles northwest of our Minnesota plots. Three adults were reared in 1971 from cocoons collected in a Beltrami County plot. These parasites came frotn hosts attacked in 1970 and therefore could not be attributed to our 1971 releases. Single specimens were reared from collections in plots in Koochiching and Lake of the Woods Counties in 1972. These plots were 10 miles or more from our 1971 release plots. These are the first records of natural spread of the parasite into the United States. Both because of the natural spread of 0. benefactor into Minnesota and because of the successful establishment of both parasites in Manitoba in similar habitats, we feel that these parasites are likely to be permanently established in Minnesota. Without the Canadian history of establishment, we would be concerned that our recovery of the parasites might only represent temporary establishment as defined by DeBach and Bartlett (1965). ACKNOWLEDGMENTS We wish t o  thank William J. Turnock and James A. Muldrew of the Canadian Department of the Environment for their advice and help in every aspect of the study. We also wish t o  thank John Beck of the Boise Cascade Corp., and Gerald Beach of the Minn. Dept. of Agr. for their cooperation. We are especially appreciative of Lee Grim and Rainy River State Junior College for their help and the use of their facilities. The Minnesota Departments of Natural Resources and Agriculture supplied supporting grants. LlTERATURE CITED DeBach, P., and B. R. Bartlett. 1965. Methods of colonization, recovery and evaluation. p. 402-426. In: P. DeBach (ed.) Biological control of insect pests and weeds. Reinhold Publishing Corp., New York. 2The Great Lakes Entomologist, Vol. 7, No. 1 [1974], Art. 6https://scholar.valpo.edu/tgle/vol7/iss1/61974 THE GREAT LAKES ENTOMOLOGIST 25 Drooz, A. T. 1974. The status of Mesoleius tenthredinis and other parasites of the larch sawfly in the eastern United States. Envir. Entomol. 3 (in press). Embree, D. G. and G. R. Underwood. 1972. Establishment in Maine, Nova Scotia, and New Brunswick of Olesicampe benefactor (Hymenoptera: Ichneumonidae), an intro- duced ichneumonid parasite of the larch sawfly, Pristiphora erichsonii (Hymenoptera: Tenthredinidae). Can Entomol. 104:89-96. Muldrew, J. A. 1953. The natural immunity of the larch sawfly Pristiphora erichsonii (Htg.) to the introduced parasite Mesoleius tenthredinis Morley, in Manitoba and Saskatchewan. Can. J. Zool. 31:313-332. Turnock, W. J. and J. A. Muldrew. 1971. Pristiphora erichsonii (Htg.), the larch sawfly (Hymenoptera: Tenthredinidae). In Biological Control programs against insects and weeds in Canada 1958-1968. Commonw. Inst. Biol. Contr. Tech. Comm. No. 4. Turnock, W. J. 1973. Geographical and historical variability in population patterns and life systems of the larch sawfly. Can. Entomol. 104: 1883-1900. BOOK REVIEW "AN INDEX TO THE DESCRIBED LI1:E HISTORIES, EARLY STAGES AND HOSTS OF THE MACROLEPIDOPTERA OF THE CONTINENTAL UNITED STATES AND CANADA,'' by Harrison Morton Tietz, 1972. Two volumes, 1041 p., published by A. C. Allyn for the Allyn Museum of Entomology, Sarasota, Florida. Distributed exclusively in North America by Entomological Reprint Specialists, P.O. Box 77971, Dockweiler Station, Los Angeles, California 90007. Price: $25.00 U.S. per set. This monumental Index is the f i s t  attempt to prepare a bibliography of the immature stages of North American butterflies and moths since Edward's Bibliographical Catalogue o f  the Described Transformations o f  North American Lepidoptera, published in 1889. The compilation includes Edward's work and published data through sometime in 1950 when the manuscript was initiated. Except for an introduction by William D. 1:ield and J .  F. Gates Clarke, both of the National Museum of Natural History, there is no introduction or other prefacing remarks by the author. The Index is divided into two parts: Part I-Insects, and Part 11-Plants, although Volume 1 contents, representing about half the total number of pages, continues into Volume 2. Under Part 1 ,  there are three sections: A-Works Consulted (periodicals, separate works, bibliographies); B-Insect Common Names and C-Macrolepidoptera. Included in the latter section are the names of all species, subspecies and forms, including synonyms, alphabetically listed with cross-references to  the main entry. The nomenclature follows that of McDunnough's 1938 Check List o f  the Lepidoptera o f  Canada and the United States o f  America: Part I ,  Macrolepidoptera. Each main entry is followed with synonyms, forms and subspecies, bibliography of published life history references and list of food plants. This section represents the greatest number of pages in the Index, and is one of the most valuable to  the researcher. Part 11 includes five sections: A-Zoological Hosts; B-Common Names; C-Indefinite Designations; D-Scientific Names; E-Synonyms. It would appear that Section D is most useful as it lists host plants and their "Insect Enemies." The plants are listed alphabetically by genus and species with the common namc, followed with a list of all known macrolepidoptera arranged by family. When the scicntific name of the plant is unknown, it can be located in Section B under the common name. Undoubtedly, this Index will be a valuablc rcference to professional and serious amateur lepidopterists, especially those engaged in life history studies or rearing activities. It will enable anyone to quickly determine whethcr or not life history or  food plant 3Kulman et al.: Introduction of Parasites of the Larch Sawfly in MinnesotaPublished by ValpoScholar, 1974

Introduction of Parasites of the Larch Sawfly in Minnesota

ValpoScholar

The Great Lakes Entomologist 
Volume 7 
Number 1 -- Spring 1974 Number 1 -- Spring 
1974 
Article 6 
March 1974 
Introduction of Parasites of the Larch Sawfly in Minnesota 
H M. Kulman 
University of Minnesota 
L. C. Thompson 
University of Minnesota 
J. A. Witter 
University of Minnesota 
Follow this and additional works at: https://scholar.valpo.edu/tgle 
 Part of the Entomology Commons 
Recommended Citation 
Kulman, H M.; Thompson, L. C.; and Witter, J. A. 1974. "Introduction of Parasites of the Larch Sawfly in 
Minnesota," The Great Lakes Entomologist, vol 7 (1) 
Available at: https://scholar.valpo.edu/tgle/vol7/iss1/6 
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. 
THE GREAT LAKES ENTOMOLOGIST 
INTRODUCTION OF PARASITES OF THE 
LARCH SAWFLY IN  MINNESOTA^ 
H. M. Kulman, L. C. Thompson, and J. A. witter2 
Department of Entomology, Fisheries, & Wildlife 
University of Minnesota, St. Paul, Minnesota 5 5 1 0 1  
ABSTRACT 
Olesicampe benefactor Hinz and the Bavarian strain of Mesoleius tenthredinis Morley, 
European ichneunionid parasites of the larch sawfly, Pristiphora erichsonii (Hartig), were 
introduced into northern Minnesota from Manitoba in 1971 and 1972. Both species are 
now established. There was also natural spread of 0. benefactor into Minnesota from 
Manitoba releases in 1961 at a point ca. 200 miles northwest of the Minnesota plots. 
Minnesota has over one-half million acres of commercial forests in the tamarack (Larix 
laricina) timber type. Although greatly under utilized, it is an important resource reserve 
for forest industries. The only major pest of tamarack in Minnesota is the larch sawfly, 
Bistiphora erichsonii (Hartig), a univoltine tenthredinid defoliator. 
Turnock (1973) describes the larch sawfly outbreaks in central and eastern North 
America as "permanent types" characterized by severe, widespread and prolonged out- 
breaks. The parasite fauna is composed of only a few species which have little influence 
on the populations. Tumock points out that there was a break in this pattern lasting 
from about 1920 to 1938 when the introduced parasite, Mesoleius tenthredinis Morley, 
was effective. During this period the population system was of the "temporary type" 
with widely fluctuating outbreaks of short duration. The demise of the temporary type in 
the late 1930's was associated with the appearance of resistance in the sawfly to the 
parasite via egg encapsulation (Muldrew 1953). The resistant strain of the sawfly is now 
dominant in most of the United States and Canada (Drooz 1973). 
Since experience with Mesoleius indicated that the permanent type can be replaced by 
the less destructive temporary type of outbreak pattern, Canadian entomologists sought 
additional European parasites for release. They succeeded with the introductions of two 
European ichneumonids, Olesicampe benefactor Hinz and an encapsulation resistant strain 
of'Mesoleius tenthredinis from Bavaria (Turnock and Muldrew 1971). Since the original 
and Bavarian strain are indistinguishable in morphology, their successful introduction was 
authenticated by the relative frequency of effective parasitization by M. tenthredinis. 
Parasitization increased from less than 10% to 30% and 60% in two different release 
plots. 
Olesicampe benefactor was also a successful parasite, attacking over 90% of the 
sawflies in several release locations. In addition, it has a remarkably good dispersal ability 
and presently can be found within ca. a 200 mile diameter area centered at  a point 100 
miles north of Minnesota on the Manitoba-Ontario border (Muldrew, personal communi- 
cation). Although it has a highly effective hyperparasite, Mesochorus dimidiatus Hlgr., 0 .  
benefactor promises to be an important parasite of the larch sawfly (Twnock and 
Muldrew 1971). 
Because of the success of the Manitoba introductions and the successful introduction 
of Olesicampe benefactor into Nova Scotia, New Brunswick, and Maine (Embree and 
Underwood 1972), the Minnesota Department of Natural Resources and the University of 
Minnesota started a program to introduce both 0. benefactor and the Bavarian strain of 
M. tenthredinis into Minnesota. In addition to the protection of our tamarack resource, 
the goals of the program are to determine the dispersal of these parasites, their 
interaction with the existing parasite fauna, and to determine the subsequent response in 
tamarack growth resulting from anticipated reductions in defoliation. These factors are 
- 
l ~ a p e r  No. 8241, Scientific Journal Series, Minnesota Agricultural Experiment Sta- 
tion, St. Paul, Minnesota. 
l ~ i t t e r  is now at the School of Natural Resources, University of Michigan, Ann 
Arbor 48104. 
1
Kulman et al.: Introduction of Parasites of the Larch Sawfly in Minnesota
Published by ValpoScholar, 1974
24 THE GREAT LAKES ENTOMOLOGIST Vol. 7, No. 1 
important for future management of sawfly populations and to help develop guidelines 
for biological control of other sawflies. 
METHODS 
About 75,000 late instar larch sawfly larvae were collected from areas in Manitoba 
known t o  be heavily parasitized by either Olesicarnpe benefactor or Mesoleius 
tentlzredinis. Larvae were reared in cages with tamarack foliage until cocoons were 
formed. After storage in sphagnum moss at 1°C, the cocoons were placed in groups of 20 
in petri dishes and kept a t  15'C until adult parasites emerged. The parasites of each 
species were placed in a 1 sq. foot mating cage for 2-4 days and then released in sawfly 
infested stands in north central Minnesota in 1971 and 1972 (Koochiching, Beltrami, 
Itasca and Lake of the Woods counties). We used 16 stands of 4 or more acres each, 
spaced 5 or more miles apart. Four plots received approximately 100 mated 0. 
benefactor females; 4 plots received approximately 350 mated 0. benefactor females; 4 
plots approximately 110 mated M. tentlzredinis females and 4 plots were used as controls. 
RESULTS AND DISCUSSION 
Preliminary results from the study plots have shown that: 
(1) Olesicarnpe benefactor has been established in Minnesota from our releases. In 
1972, 3 specimens were reared from 2 of the 4 plots where 100 parasites were released 
and 25 specimens in 3 of the 4 plots that received 350 parasites. ,On the basis of the size 
of overwintering cocoons, we anticipate that all four of the 350-parasite release plots will 
show increases in 1973. 
(2) The Bavarian strain of Mesoleius tentlzredinis has been established in Minnesota 
from our releases. Prior to 1972 all plots had less than 10% parasitization by Mesoleius. In 
1972, 2 of the 4 release plots showed increases in parasitization from 10 to about 30%. 
All other 14 plots remained a t  less than 10%. 
(3) There has been natural spread of Olesicarnpe benefactor into Minnesota from the 
1961 releases near Pine Falls Manitoba ca. 200 miles northwest of our Minnesota plots. 
Three adults were reared in 1971 from cocoons collected in a Beltrami County plot. 
These parasites came frotn hosts attacked in 1970 and therefore could not be attributed 
to our 1971 releases. Single specimens were reared from collections in plots in 
Koochiching and Lake of the Woods Counties in 1972. These plots were 10 miles or 
more from our 1971 release plots. These are the first records of natural spread of the 
parasite into the United States. 
Both because of the natural spread of 0. benefactor into Minnesota and because of 
the successful establishment of both parasites in Manitoba in similar habitats, we feel that 
these parasites are likely to be permanently established in Minnesota. Without the 
Canadian history of establishment, we would be concerned that our recovery of the 
parasites might only represent temporary establishment as defined by DeBach and 
Bartlett (1965). 
ACKNOWLEDGMENTS 
We wish t o  thank William J. Turnock and James A. Muldrew of the Canadian 
Department of the Environment for their advice and help in every aspect of the study. 
We also wish t o  thank John Beck of the Boise Cascade Corp., and Gerald Beach of the 
Minn. Dept. of Agr. for their cooperation. We are especially appreciative of Lee Grim and 
Rainy River State Junior College for their help and the use of their facilities. The 
Minnesota Departments of Natural Resources and Agriculture supplied supporting grants. 
LlTERATURE CITED 
DeBach, P., and B. R. Bartlett. 1965. Methods of colonization, recovery and evaluation. 
p. 402-426. In: P. DeBach (ed.) Biological control of insect pests and weeds. Reinhold 
Publishing Corp., New York. 
2
The Great Lakes Entomologist, Vol. 7, No. 1 [1974], Art. 6
https://scholar.valpo.edu/tgle/vol7/iss1/6
1974 THE GREAT LAKES ENTOMOLOGIST 25 
Drooz, A. T. 1974. The status of Mesoleius tenthredinis and other parasites of the larch 
sawfly in the eastern United States. Envir. Entomol. 3 (in press). 
Embree, D. G. and G. R. Underwood. 1972. Establishment in Maine, Nova Scotia, and 
New Brunswick of Olesicampe benefactor (Hymenoptera: Ichneumonidae), an intro- 
duced ichneumonid parasite of the larch sawfly, Pristiphora erichsonii (Hymenoptera: 
Tenthredinidae). Can Entomol. 104:89-96. 
Muldrew, J. A. 1953. The natural immunity of the larch sawfly Pristiphora erichsonii 
(Htg.) to the introduced parasite Mesoleius tenthredinis Morley, in Manitoba and 
Saskatchewan. Can. J. Zool. 31:313-332. 
Turnock, W. J. and J. A. Muldrew. 1971. Pristiphora erichsonii (Htg.), the larch sawfly 
(Hymenoptera: Tenthredinidae). In Biological Control programs against insects and 
weeds in Canada 1958-1968. Commonw. Inst. Biol. Contr. Tech. Comm. No. 4. 
Turnock, W. J. 1973. Geographical and historical variability in population patterns and 
life systems of the larch sawfly. Can. Entomol. 104: 1883-1900. 
BOOK REVIEW 
"AN INDEX TO THE DESCRIBED LI1:E HISTORIES, EARLY STAGES AND HOSTS 
OF THE MACROLEPIDOPTERA OF THE CONTINENTAL UNITED STATES AND 
CANADA,'' by Harrison Morton Tietz, 1972. Two volumes, 1041 p., published by A. C. 
Allyn for the Allyn Museum of Entomology, Sarasota, Florida. Distributed exclusively in 
North America by Entomological Reprint Specialists, P.O. Box 77971, Dockweiler 
Station, Los Angeles, California 90007. Price: $25.00 U.S. per set. 
This monumental Index is the f i s t  attempt to prepare a bibliography of the immature 
stages of North American butterflies and moths since Edward's Bibliographical Catalogue 
o f  the Described Transformations o f  North American Lepidoptera, published in 1889. 
The compilation includes Edward's work and published data through sometime in 1950 
when the manuscript was initiated. Except for an introduction by William D. 1:ield and J .  
F. Gates Clarke, both of the National Museum of Natural History, there is no 
introduction or other prefacing remarks by the author. 
The Index is divided into two parts: Part I-Insects, and Part 11-Plants, although 
Volume 1 contents, representing about half the total number of pages, continues into 
Volume 2. Under Part 1 ,  there are three sections: A-Works Consulted (periodicals, 
separate works, bibliographies); B-Insect Common Names and C-Macrolepidoptera. 
Included in the latter section are the names of all species, subspecies and forms, including 
synonyms, alphabetically listed with cross-references to  the main entry. The nomenclature 
follows that of McDunnough's 1938 Check List o f  the Lepidoptera o f  Canada and the 
United States o f  America: Part I ,  Macrolepidoptera. Each main entry is followed with 
synonyms, forms and subspecies, bibliography of published life history references and list 
of food plants. This section represents the greatest number of pages in the Index, and is 
one of the most valuable to  the researcher. 
Part 11 includes five sections: A-Zoological Hosts; B-Common Names; C-Indefinite 
Designations; D-Scientific Names; E-Synonyms. It would appear that Section D is most 
useful as it lists host plants and their "Insect Enemies." The plants are listed 
alphabetically by genus and species with the common namc, followed with a list of all 
known macrolepidoptera arranged by family. When the scicntific name of the plant is 
unknown, it can be located in Section B under the common name. 
Undoubtedly, this Index will be a valuablc rcference to professional and serious 
amateur lepidopterists, especially those engaged in life history studies or rearing activities. 
It will enable anyone to quickly determine whethcr or not life history or  food plant 
3
Kulman et al.: Introduction of Parasites of the Larch Sawfly in Minnesota
Published by ValpoScholar, 1974


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Introduction of Parasites of the Larch Sawfly in Minnesota

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