©lie Pmtarsti|j of ^rtttsij (Eolomdbia Faculty of Graduate Studies PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY "t RAYMOND JOSEPH FINNEGAN B.Sc.F. New Brunswick 1948 M.Sc.F. New Brunswick 1950 IN ROOM 187A BIOLOGICAL SCIENCES BUILDING Saturday, November 8, 1958 9:30 a.m. COMMITTEE IN CHARGE DR. F. H. SOWARD, Chairman K. GRAHAM G. S. ALLEN I. McT. COWAN J. E. BIER P. A. LARKIN V. KRAJINA DEAN W. H. GAGE External Examiners of Thesis JOHN MacSWAIN (Univ. of California) JULIUS A. RUDINSKY (Oregon State College) W. G. WELLINGTON (Division of Forest Biology) ECOLOGICAL STUDIES OF HYLOBIUS RAD1C1S BUCH., H. PALES (HBST.) AND PISSODES APPROXIMATUS HOPK. (COLEOPTERA: CURCULIONIDAE) IN SOUTHERN ONTARIO. ABSTRACT Three native weevils have become increasingly important in recent years in stands of planted pines in southern Ontario. The pine root collar weevil, Hyldbius radicis finch., breeds in the root collar of healthy pines, killing over 90% of the trees in some plantations. The pales weevil, H. pales (Hbst.), and the northern pine weevil, Pissodes approximates Hopk., are important because the adults, feeding on the tender bark of twigs and small branches of healthy pines, kill the branches or even the whole tree. The life histories and bionomics of the three species were determined from natural populations in the field and colonies in the insectary. These studies were facilitated by a special technique devised for rearing the weevils permitting continuous observation's of larval and pupal development and periodic measurement of body size and larval feeding. Stand density is the chief factor regulating populations: of H. radicis, fostering high populations in the dense stands of plantations, and excluding the insect from sparser natural stands. Scots pine is evidently more susceptible than red pine to H. radicis where the two tree species grow together, but the presence of Scots pine increases the infestation in red pine. Availability of suitable breeding material in the form of numerous stumps left after cutting is the factor governing the number of H. pales and P. approximates. The implications for forestry consist of recom• mendations to avoid pure dense stands especially of exotic species, and to practice forest sanitation in cutting operations. PUBLICATIONS STEWART, K. E., R. J. FINNEGAN AND C. S. KIRBY. Control of Fletcher scale, Lecanium fletcheri Ckll., on Japanese yew. Can. Dept. Agr., For. Biol. Div., Bi-Monthly Prog. Rept. 9 (2): 3. 1953. FINNEGAN, R. J. Weevils attacking pines in southern Ontario. Can. Dept. Agr., For. Biol. Div., Bi-Monthly Prog. Rept. 12(2): 3. 1956. FINNEGAN, R. J. Elm bark beetles in southern Ontario. Canad. Ent. 89 (6): 275-280. 1957. FINNEGAN, R. J. The pine weevil, Pissodes approximates Hopk., in southern Ontario. Canad. Ent. 90(6): 384-354. 1958. Faculty of Graduate Studies PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY RAYMOND JOSEPH FINNEGAN B.Sc.F. New Brunswick 1948 M.Sc.F. New Brunswick 1950 IN ROOM 187A BIOtOGICAL SCIENCES BUILDING Saturday, November 8, 1958 9:30 a.m. COMMITTEE IN CHARGE DR. F. H. SOWARD, Chairman K. GRAHAM G. S. ALLEN I. McT. COWAN J. E. BIER P. A. LARKIN V. KRAJINA DEAN W. H. GAGE External Examiners of Thesis JOHN MacSWAIN (Univ. of California) JULIUS A. RUDINSKY (Oregon State College) W. G. WELLINGTON (Division of Forest Biology) ECOLOGICAL STUDIES OF HYLOBWS RADICIS BUCH., H. PALES (HBST.) AND PISSODES APPROXIMATUS HOPK. (COLEOPTERA: CURCULIONIDAE) IN SOUTHERN ONTARIO. ABSTRACT Three native weevils have become increasingly important in recent years in stands of planted pines in southern Ontario. The pine root collar weevil, Hylobius radicis Buch., breeds in the root collar of healthy pines, killing over 90% of the trees in some plantations. The pales weevil, H. pales (Hbst.), and the northern pine weevil, Pissodes approximatus Hopk., are important because the adults, feeding on the tender bark of twigs and small branches of healthy pines, kill the branches or even- the whole tree. The life histories and bionomics of the three species were determined from natural populations in the field and colonies in the insectary. These studies were facilitated by a special technique devised for rearing the weevils permitting continuous observations of larval and pupal development and periodic measurement of body size and larval feeding. • Stand density is the chief factor regulating;.;populations; of H. radicis, fostering high populations in the dense stands of plantations, and excluding the insect, from sparser natural stands. Scots pine is evidently more susceptible than red pine to H. radicis where the two tree rspecies* grow together,. but the presence of Scots pine increases the infestation in red pine. Availability of suitable breeding material in the form of numerous stumps left after cutting is the factor governing the number of H. pales and P. approximatus. The implications for forestry consist of recom• mendations to avoid pure dense stands especially of exotic species, and to practice forest sanitation in cutting operations. PUBLICATIONS STEWART, K. E., R. J. FINNEGAN AND C. S. KIRBY. Control of Fletcher scale, Lecanium fletcheri Ckll., on Japanese yew. Can. Dept. Agr., For. Biol. Div., Bi-Monthly Prog. Rept. 9 (2): 3. 1953. FINNEGAN. R. J. Weevils attacking pines in southern Ontario. Can. Dept. Agr., For. Biol. Div., Bi-Monthly Prog. Rept. 12(2): 3. 1956. FINNEGAN, R. J. " Elm bark beetles in southern Ontario. Canad. Ent. 89 (6): . 275-280. 1957. FINNEGAN, R. J. The pine weevil, Pissodes approximates Hopk., in' southern Ontario. Canad. Ent. 90(6): 384-354. 1958. ECOLOGICAL STUDIES OF HYLOBIUS RADICIS BUCH., H. PALES (HBgT.) AND PISSODES APPROXIMATUS HOPK. (COLEOPTERA : CURCULIONIDAE) IN SOUTHERN ONTARIO. lay RAYMOND JOSEPH FINNEGAN B. Sc. (F.) 1948, University of New Brunswick. M. Sc. (P.) 1950, University of New Brunswick. A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Zoology We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September, 1958. ABSTRACT Three native weevils have "become increasingly important in recent years in stands of planted pines in southern Ont• ario. The pine root collar weevil, Hylobius radicis Buch., breeds in the root collar of healthy pines;, killing over SO<fo of the trees in some plantations. The pales weevil, H. pales. (Host.), and the northern pine weevil, Pissodes a-p-proximatus Hook.» are important because the adults, feeding on the tender bark of twigs and small branches of healthy pinest kill the branches or even the whole tree. The life histories and bionomics of the three species were determined from natural populations in the field and colonies in the insectary. These studies were facilitated by a special technique devised for rearing the weevils permitting continuous observations of larval and pupal development and periodic measurment of body size and larval feeding. Stand density is the chief factor regulating popula• tions of H. radicis, fostering high populations in the dense stands of plantations, and excluding the insect from sparser natural stands. Scots pine is evidently more susceptible than red pine to H. radicis where the two tree species grow together, but the presence of Scots pine increases the infes- iii tation in red pine. Availability of suitable breeding material in the form of numerous stumps left after cutting is the factor governing the number of H. pales and P. approximatus. The implications for forestry consist of recommendations to avoid pure dense stands especially of exotic species, and to practice forest sanitation in cutting operations. In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representative. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver 8, Canada. iv CONTENTS Page INTRODUCTION 1 TAXONOMY 4 METHODS 10 Study of Insect Biologies 10 Measurment of Damage 15 HYLOBIUS RADICIS BUCK 19 History 19 Description of Life History Stages 21 Distribution and Hosts 29 Seasonal History 50 Habits • 34 Limiting Factors 42 Effect on the Tree 46 HYLOBJJJS PALES (HBST.) 56 History 57 Description of Life History Stages 59 Distribution and Hosts 64 Seasonal History 67 Habits 71 Limiting Factors 74 Effect on the Tree 77 V PISSODES APPROXIMATUS HOPE 78 History . .. 78 Description of Life History Stages t. 1... 79 Distribution and Hosts 83 Seasonal History 84 Habits t- i. 85 Limiting Factors *... i ... 91 Effect on the Tree' 94 DISCUSSION AND ^CONCLUSIONS .. ..; : 95 BIBLIOGRAPHY 103 FIGURES Fig. 1. Method,;.of rearing pine weevils in the insectary from the egg to the adult stage showing, (a) pouring the sa'nd over the * inner bark and screen; (b) a sectional view of the rea'ring unit 12 Fig. 2. Larvae of Hylobius radicis in rearing (a) Feeding larva, (b) Prepupa in pupal -r cell 14 Fig. 3. Caged pine trees used in studying the bionomics of Hylobius radicis 17 Fig. 4. Hylobius radicis. (a) Egg x24; (b) Larva x6; (c) Pupa in earthen cell x6; (d) Adult x6 22 Fig. 5. Dorsal view of (a) Hylobius radicis and (b) H. pales, showing the* scattered spots'' on the elytra of H. radicis in contrast to the barred pattern on the elytra of H. pales .. ..... 23 vi Pig. 6. (a) Hind tibial uncus of Hylobius radicis males; (b) Hind tibial uncus of H. -pales males; (c) Hind tibial uncus °f H» radicis and H.