Richmond, H. A.

English

Journal of the Entomological Society of British Columbia

ENTOMOLOGICAL SOC. OF BBIl'ISII COLU')IllIA, PRoc. (1946), VOL. 43, FEB. 4, 1947 33 CURRENT TREND OF THE WESTERN HEMLOCK LOOPER (LAMBDINA F. LUGUBROSAl IN THE COASTAL FO'RESTS OF BRITISH COLUMB IA (Lepidoptera, Geometridae) 1 H. A. RICHMOND Dominion Forest Insect Laboratory, Victoria, B.C. An outbreak of the western hemlock looper (Lambdina fiscellaria lugubrosa H lst.) reached serious proportions in sec-tions of the coastal forests of British Co-lumbia during 1945. Only in that year was damage of this present cycle partic-ularly noticeable and as indicated below there was little evidence of any degree of natural control. Further destruction of timber is expected Juring 1946. This current outbreak represents the first appearance of the looper since the large outbreak of 1930. Although records of this insect date back to 1882 (de Gryse, 1934:523-527) it is only in reccnt years that specific data have been recorded on the prevalence of this insect in British Columbia. While these records are not necessarily complete, they indicate past outbreaks as follows: Stanley Park 1911-13 (Swaine, 1918) ; Vancouver Island 1913 - 14 (Jaenicke, 1929); Quatsino Sound, Vancouver Island 1925 (recounted by residents); south coastal mainland 1928-30 (Hopping, 1934: 12-13); and in the Interior, the Big Bend of the Columbia River and Nakusp region 1937-38 (unpublished records). The last coastal outbreak subsided in 1930, but records of the occurrencc of the hemlock looper ha ve b ~(:' n ohtaincd e;:teh year s:nce 193 i, the ~'ear of the inaugur-a!ion of the ForL'st In ieet Survey in British C cl umhia. The pre~cnt cycle first came into prom-inence in 194+, wh c'n the looper appeared in moderate numht'rs in the Lens Creek valley (upper San Juan drain;:tge) al-though it was undouhtedh· in creasing in other areas where Sl'Vl'J'C defol iation oc-curred in 1945. 1 Contribution No. 2442 . Division of Entomology, ~ "·e ll .. Serv:ce, Dep:lI' ~ lll ent of A -ricLllt;;re. Ottawa. C, II .::a. During 1945 the major infestation occurred on the south west portion of Vancouver Island extending roughly from San Juan River north to the Alberni In-let, an area of some 900 square miles. Throughout this region severe defoliation was irregularly distributed as is typical of looper attack. Viewed from the air in March 1946, some 140 square miles of timber appeared to be almost totally stripped of foliage. The timber concerned is some of the best of the west coast hemlock and Douglas fir. The most widespread infesta-tion occurred in the Caycuse River valley, where extremely heavy defoliation ex-tended from the mOLlth of the river on Lake Nitinat to its headwaters at McClure Lake and through to the headwaters of Walbran Creek. From the Caycuse it swept into the Nitinat valley where 400 million feet of timber are infested. North of the Nitinat an infestation as serioLls as that in the Caycuse valley, is centred in the Klanawa River valley, and covers some 12 square miles. Further infestations occur in the Pach ena valley (moderate), lower Sarita (very severe), and at Coleman Cl eek (heavy). Endemic looper popula-t; ons were recorded at the headwaters of th e San Juan River, Lens Creek, Port San Juan, and Carmanah Creek. On the . mainland further a t t a c k was reported from Clowhom Lake near Sechelt Inlet and in two art'a.' on th e Greater Vancou-·ITr wa tersh ed. C u RENT L OOPER SrTuATION.- Pres-ent indica tions point to a "ery marked in-creas ,' 111 looper pq m\ation in 1')+6 on the has's of ol'erwintering egg counts. In sll ': h examinations, four areas were con-sidered, the Cayeuse vall ey, Nitinat valley, Pac hena and Coleman Creek. \Vhil e the past history of these in f estations is not definite, P:1 ' hena alone appears to he of 34 EXTO~IOLOGICAL Soc. OF BRITISH COLl; ~IlJIA, Puoe. (1946), VOL. 43, FEll. 4, 1947 1945 Origin, the others are probably two years old. Egg population data were ob-tained through the examination of moss samples, taken from tree trunks at 20 foot intervals from ground level to the top. Old egg shells were recorded as well as sound eggs from which a ratio waS obtained between remaining egg chorions of previous years, and the overwintering eggs of the current year. While there is no suggestion that such a ratio indicates the true increase for 1946, it is of interest in a relative sense in comparing one area with another. D efoliation figures were deriyed by examination of 1/5 acre plots adjacent to trees analyzed for egg counts. A summary of these averages follows: aged 82 70 wit h an egg count of 226 sOllnd eggs per sqllare foot of moss at 80 feet elevation. At 1400 feet mean defoli-ation was 10 % ~ith 0.3 eggs per square foot of moss. The lack of a direct corre-lation between absolute elevation and looper abundance, however, eliminates any hard and fast rule in sampling a stand for mean defoliation. There appears, furthermore, a marked variation in population according to light intensity. Dominant trees averaged 10% higher defoliation than intermediate trees and there was consistently greater feeding and more eggs in trees near forest open-ings adjacent to streams and swamps. TABLE I.-Defoliation and Eggs in Moss, Western Hemlock Looper. Per Cent Defoliation AV. EGGS PER SQ. FOOT MOSS Ratio Between Old & Current Eggs AREA of Hemlock Old Chorions Current Eggs Caycuse ... . . .. ... . . ... .. .. . . . . .... 62 Nitinat . . . . . . . . . . . . . . . . . . . • . . . . . . .. 51 Pachena .. . .. .. .... . ... .. . ... .. . ... 47 Coleman Cr. ................. . ..... 81 These figues represent conditions only at the points sampled and defoliation per-centages should not be considered as typ-ical of the entire area. There is a sugges-tion of a fairly serious situation for 1946, since it is felt that these indications are in no wayan exaggeration of the overall picture. Nevertheless, s u c h calculations cannot be regarded as more than approxi-mations without extensive and adequate sampling, considering relative elevations, forest density and light intensity. In estimating populations, the absolute elevation may not be as important as the relative height in a valley system. Thus the floor of the upper Caycuse valley, 750 feet elevation, was as severely defoliated as that of the Nitinat at 80 feet. In higher tributary valleys this characteristic was still evident in the severe attack in the gullies of small streams. That elevations are of minor importance, however, is not suggested, since in the Nitinat where 20 sampling points were selected with 92 moss samples examined, defoliation aver-12.0 7.5 5.1 22.0 96.0 95 .2 55 .0 96.0 1: 8.0 1:12.7 1 :10.8 1: 4.4 NATURAL CONTROL.- R e c or d s ob-tained from the Caycuse valley, the oldest apparent infested region in 1945, showed a larval parasitism of 5 % and pupal para-sitism somewhat less. No egg parasites were found in 1259 eggs incubated in ] anuary 1946. 0 f another 2000 eggs collected in March 1946, 93 % hatched and no parasites were recorded. Neither de Gryse (1934) nor Watson (1934) re-ported parasites of primary importance in looper outbreaks in eastern Canada. Hop-ping (1934) recorded 14 species of para-sites on the coast of British Columbia, but a high of only some 21 % parasitism of larvae and pupae combined. He did, however, obtain 25 % parasitism of eggs in the Seymour Arm region. In the light of the past records and in view of the trend suggested by current winter investi-gations, there appears to be little likeli-hood of any immediate slackening in the present hemlock looper situation. The eventual termination of the current cycle through the prevalence of disease IS a EXTOMOLOGIC.\LSOC. OF BRITIS H COU; ,wu. PROL (1946), VOL. 43, FElL 4, 1947 35 strong .. possibility, · since there were minor indica tions of the appea rance of disease in 1945. It is yet too ea rly, however, to p:'edic t th e trend of insect diseases and the f uture of this present outbreak of the hemlock looper. LITERATURE CITED lie Gryse, J. J. and K. Schedl, 1934. An account of the eastern hemlock looper, Ellopia fiscellaria Gn., on hemlock, with notes on allied species. Sci. Agr. 14:523-539. Hopping, G. R. 1934. An account of the western hemlock looper, Ellopia somniaria Hulst., on conifers in British Columbia. Sci. Agr. 15:12-29. J<Lenicke, A. J. 1929. Th.e western hemlock looper. Four L Lumber News 11 :16-20. Swaine, J. M. 1918. Insect injuries to forests in British Columbia, Chapter X , p . 220-37 in: Forests of British Columbia by H . N. Whitford and R. D. CTaig, Commission of con-servation, ottawa. ,"ratson, E. B. 1934. An account of the eastern hemlock looper, Ellopia fiscellaria Gn., on balsam fir. Sci. Agr. 14:669-678. RESUME O'F INFESTATIONS AND CONTROL OF THE COLORADO POTATO BEETLE IN BRITISH COLUMBIA, 1911-1946. 1. J. WARD Provincial Entomologist, Vernon, B.C. The potato beetl e (L"pti llotarsa riecem-lineata (Say) ) was first recorded in Brit-ish Columbia in 19 11 at Newgate on the International Boundary in the extreme south-eastern port i<m of th e Prov ince. It appears that this infestation originated fr()m the adjoining Stat~ of Montana. No systematic eradica tion or cont rol mea~~ures we re adopted when th t: pest was fi rs t observed and the are;. of in festation grew considerably yea" by year. In 1922 E. C. Hunt, District Horticulturist, Nelson, B.C. , and J. W. Eastham, Provincial Plant Path ologist, mad e a survey of the N ewgate country an d recommended that help he given to the growers. The follow-ing year control measures were ' adopted to a limited degree. In 1926 the Dominion Entomological Branch in co-operation with the Pr()vincial Department- of Agr icu lture underto()k to investigate the extent of the potato beetl e infestation and to work out a systematic comol program . The distri ct then infested consisted of two areas : ( I) The larger area extended from Newgate north to F ernie and north-west through Cranbrook to Premier Lake in the K ontenay-Columhia Valley. (2) The slnall er area exten.ded from R ykerts, B.C. on the International Boundary north to Creston and Wynndel. It is believed that this infestation came to the Creston district; some sixty (airline) miles west of N ew-ga te, from the State of Idaho to th e south durin g 1923 or 1924. The tdal area in f ested in the two dis-tricts amnunted to approximately 66 5 sljuare mil es in which some tl80 acres of pctatoes were grown. Supervised control m easures were under-taken in 1927 and a total 0 f 32,965 pounds of calc ium arsenate 1-6 dust were w ed du ring the year. The late A. A. D ennys of the D ominion Division of En-tomology was placed in charge. A reduc-tion in th e intensity of the infestation was noted. During the foll owing year a spot infestation occurred 100 mil es f arther afi eld nea r Golden, B.C., in the upper Cc-1umbia Valley. This area was d.4sted th oroughly hy ML D ennys and up until this year ( 1946 ) there has hee n no I;ecur~ rence 0 f the in festation. In spite of improved and annual control, new in festations have occurred from time to time inisolated.parts of southern British C()lumbia. In the early .J9 :HJ'sa spot ' in~ 

Current trend of the western hemlock looper (Lambdina f. lugubrosa) in the coastal forests of British Columbia (Lepidoptera, Geometridae)

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Current trend of the western hemlock looper (Lambdina f. lugubrosa) in the coastal forests of British Columbia (Lepidoptera, Geometridae)

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Journal of the Entomological Society of British Columbia