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 During 1945 the major infestation looper (Lambdina fiscellaria lugubrosa occurred on the south west portion of H lst.) reached serious proportions in sec­ extending roughly from tions of the coastal forests of British Co­ San Juan River north to the Alberni In­ lumbia during 1945. Only in that year let, an area of some 900 square miles. was damage of this present cycle partic­ Throughout this region severe defoliation ularly noticeable and as indicated below was irregularly distributed as is typical of there was little evidence of any degree of looper attack. Viewed from the air in natural control. Further destruction of March 1946, some 140 square miles of timber is expected Juring 1946. timber appeared to be almost totally stripped This current outbreak represents the of foliage. The timber concerned is some first appearance of the looper since the of the best of the west coast hemlock and large outbreak of 1930. Although records Douglas fir. The most widespread infesta­ of this insect date back to 1882 (de Gryse, tion occurred in the Caycuse River valley, 1934:523-527) it is only in reccnt years where extremely heavy defoliation ex­ that specific data have been re corded on tended from the mOLlth of the river on the prevalence of this insect in British Lake Nitinat to its headwaters at McClure Columbia. While these records are not Lake and through to the headwaters of necessarily complete, they indicate past Walbran Creek. From the Caycuse it outbreaks as follows: Stanley Park 1911- swept into the Nitinat valley where 400 13 (Swaine, 1918) ; Vancouver Island million feet of timber are infested. North 1913 - 14 (Jaenicke, 1929); Quatsino of the Nitinat an infestation as serioLls as Sound, Vancouver Island 1925 (recounted that in the Caycuse valley, is centred in the by residents); south coastal mainland Klanawa River valley, and covers some 1928-30 (Hopping, 1934: 12-13); and 12 square miles. Further infestations occur in the Interior, the Big Bend of the in the Pachena valley (moderate), lower and Nakusp region 1937- Sarita (very severe), and at Coleman 38 (unpublished records). Cl eek (heavy). Endemic looper popula­ The last coastal outbreak subsided in t; ons were recorded at the headwaters of 1930, but records of the occurrencc of the th e San Juan River, Lens Creek, Port hemlock looper ha ve b ~(:' n ohtaincd e;:teh San Juan, and Carmanah Creek. On the year s:nce 193 i, the ~'e ar of the inaugur­ . mainland further a t t a c k was reported a!ion of the ForL'st In ieet Survey in British from Clowhom Lake near Ccl umhia. and in two art'a.' on th e Greater Vancou­ The pre~cnt cycle first came into prom­ ·ITr wa tersh ed. inence in 194+, wh c'n the looper appeared C u REN T L OOPER SrTuATION.- Pres­ in moderate numht'rs in th e Lens Creek ent indica tions point to a "ery marked in­ valley (upper San Juan drain;:tge) al­ creas ,' 111 looper pq m\ation in 1') +6 on the though it was undouhtedh· in cre as ing in has's of ol'erwintering egg counts. In other areas where Sl'Vl'J'C defol iation o c­ sll ': h examinations, four curred in 1945. areas were con­ sidered, the Cayeuse vall ey, Nitinat valley, Pac hena and Coleman Cree k. \Vhile the 1 Contribution No. 24 42 . Division of Entomology, ~ "·e ll .. Serv:ce, Dep:lI' ~ lll ent of A -ricLllt;;re. Ottawa. past history of these in f estations is not C, II .::a. 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 aged 82 70 wit h an egg count of 226 years old. Egg population data were ob­ sOllnd eggs per sqllare foot of moss at 80 tained through the examination of moss feet el evation. At 1400 feet mean defoli­ samples, taken from tree trunks at 20 ation was 10 % ~ith 0.3 eggs per square foot intervals from ground level to the foot of moss. The lack of a direct corre­ top. Old egg shells were recorded as well lation between absolute elevation and as sound eggs from which a ratio waS looper abundance, however, eliminates obtained between remaining egg chorions any hard and fast rule in sampling a stand of previous years, and the overwintering for mean defoliation. eggs of the current year. While there is There appears, furthermore, a marked no suggestion that such a ratio indicates the true increase for 1946, it is of interest variation in population according to light in a relative sense in comparing one area intensity. Dominant trees averaged 10% with another. D efoliation figures were higher defoliation than intermediate trees deriyed by examination of 1/5 acre plots and there was consistently greater feeding adjacent to trees analyzed for egg counts. and more eggs in trees near forest open­ A summary of these averages follows: ings adjacent to streams and swamps.

TABLE I.-Defoliation and Eggs in Moss, Western Hemlock Looper.

Per Cent Ratio Defoliation AV. EGGS PER SQ. FOOT MOSS Between Old & AREA of Hemlock Old Chorions Current Eggs Current Eggs

Caycuse ...... 62 12.0 96.0 1: 8.0 Nitinat ...... • ...... 51 7.5 95 .2 1:12.7 Pachena ...... 47 5.1 55 .0 1 :10.8 Coleman Cr...... 81 22.0 96.0 1: 4.4

These figues represent conditions only NATURAL CONTROL.- R e c or d s ob­ at the points sampled and defoliation per­ tained from the Caycuse valley, the oldest centages should not be considered as typ­ apparent infested region in 1945, showed ical of the entire area. There is a sugges­ a larval parasitism of 5 % and pupal para­ tion of a fairly serious situation for 1946, sitism somewhat less. No egg parasites since it is felt that these indications are in were found in 1259 eggs incubated in no wayan exaggeration of the overall ] anuary 1946. 0 f another 2000 eggs picture. Nevertheless, s u c h calculations collected in March 1946, 93 % hatched cannot be regarded as more than approxi­ and no parasites were recorded. Neither mations without extensive and adequate de Gryse (1934) nor Watson (1934) re­ sampling, considering relative elevations, ported parasites of primary importance in forest density and light intensity. looper outbreaks in eastern Canada. Hop­ In estimating populations, the absolute ping (1934) recorded 14 species of para­ elevation may not be as important as the sites on the coast of , relative height in a valley system. Thus but a high of only some 21 % parasitism the floor of the upper Caycuse valley, 750 of larvae and pupae combined. He did, feet elevation, was as severely defoliated however, obtain 25 % parasitism of eggs as that of the Nitinat at 80 feet. In higher in the Seymour Arm region. In the light tributary valleys this characteristic was of the past records and in view of the still evident in the severe attack in the trend suggested by current winter investi­ gullies of small streams. That elevations gations, there appears to be little likeli­ are of minor importance, however, is not hood of any immediate slackening in the suggested, since in the Nitinat where 20 present hemlock looper situation. The sampling points were selected with 92 eventual termination of the current cycle moss samples examined, defoliation aver- 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 p:'edict th e trend of insect diseases and the indications of the appea rance of disease f uture of this present outbrea k of the in 1945. It is yet too ea rly, however, to 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

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"ptillotarsa riecem­ (2) The slnall er area exten.ded from lineata (Say) ) was first recorded in Brit­ R ykerts, B.C. on the International ish Columbia in 19 11 at Newgate on the Boundary north to Creston and International Boundary in the extreme Wynndel. south-eastern porti