Velutinum Leconte (Coleoptera: Cerambycidae)

62 J . E :> TOllIOI.. SoC' . BRIT. COLu ~ImA , 66 (1969), A U G. 1, 1969 hole jagged, usually with pieces of co in O. tsugae tsugae ca. 0.20 mm (0.17- coon adhering to it (Fig. 15). Hole 0.22 mm) . Stalk of spiracle shorter situated apically or subapically. Para than diameter of atrium (Fig. 12). site cocoon thin, laid down as a layer Acknowledgments on inside of host cocoon; host remains The author gratefully acknowledges the are walled off outside parasite cocoon. assistance of Miss L. M. Walkley of the Parasite final-instar remains are Insect Identification and Parasite Intro duction Branch, Agricultural Research Ser closely associated with the meconium. vice, U.S.D.A., Washington, D.C., for iden Final - instar cephalic structure tifying many of the parasites collected in (Fig. 6) similar to Mastrus spp. (Fig. connection with this ·study; and (Mrs.) Christine Andrew for assisting with slide 2), but larger; width of labial sclerite preparations and photomicrogr.aphic work. References Crosby, D. 1965. Forest insect conditions in the various regions, Alaska, p. 37. In Forest insect conditions in the United States 1964. Forest Service, U.S. Dep. Agr. 41 pp. Downing, G. L. 1957. The recent history of destructive forest insect activity in Alaska, pp. 111-116. In Science in Alaska 1957, Albert W. Johnson, ed. 8th Alaska Sci. Conf. Proc., Anchorage. Downing, G. L. 1959. Hemlock sawfly. U.S . Dep. Agr., Forest Serv., Forest Pest Leaflet 31, 4 pp. Finlayson, T. 1960a. Taxonomy of cocoons and puparia, and their contents, of Canadian parasites of Neodiprion sertifer (Geoff.) (Hymenoptera: Diprionidae). Can. Entomol. 92:20-47. Finlayson, T. 1960b. Taxonomy of cocoons and puparia, and their contents, of Canadian parasites of Diprion hercyniae (Htg.) (Hymenoptera: Diprionidae). Can. Entomol. 92: 922-941. Furniss, R. L. and P . B. Dowden, 1941. Western hemlock sawfly, Neodiprion tsugae Middleton, and its par.asites in Oregon. J. Econ. Entomol 34: 46-52. Torgersen, T. R. 1968. Parasites of the hemlock sawfly, Neodiprion tsugae, in coastal Alaska. Ann. Entomol. Soc. Amer . 61 :1155-1158. FINAL-INSTAR LAR\,AE OF TWO HYMENOPTEROUS PARASITES OF A WOOD-BORING BEETLE, TETROPIUM VELUTINUM LECONTE (COLEOPTERA: CERAMBYCIDAE) THELMA FINLAYSON I ABSTRACT Characteristics of the cephalic structures, spiracles and skin of final-ins tar larvae of two hymenopterous parasites, Helconidea occidental is (Cress.) and Rhimphoctona atrocoxalis CAshm.), whose cocoons were found in galleries of the wood-boring beetle, Tetropium velutinum LeConte, are described and illustrated. The species of wood-infesting (Ross 1967 a, b) . During the course of Coleoptera of economic importance that investigation two species of to western larch, Larix occidentaZis parasites were reared, and subse Nuttall in British Columbia were in quently a section of log from which vestigated by Dr. D. A. Ross, Forest they emerged was made available to Entomology Laboratory, Canada De the author for study. As specific in partment of Forestry, Vernon, B.C. formation on wood-boring beetles and their parasites is scarce this log from I Pestology Centre, Department of Biological SCiences, Simon Fraser University, Burnaby 2, B.C. which both beetles and parasites had J. E.H,,,rOL. Soc. BRIT. CO l.u 'ormA, 66 (1969), A U G. 1, 1969 63 emerged provided an opportunity to sections, and each section was then establish positive host-parasite rela quartered. The sections and quarters tionships. were labelled so that each beetle gal The 2.5-foot section examined was lery could be followed throughout its part of a log felled on June 16th, 19 65, en tire course. Each section of log was at Houser Ridge, near Lardeau, north chipped apart and 3-dimensional of Kootenay Lake, B.C. Adults of drawings were made so that the T etr opium ve lutinum LeConte (Cole length and type of burrows could be optera: Cerambycidae) emerged be determined. The larval entrance holes tween May 9th and June 8th, 1966, of T . velutinum a re elliptical (Ross and September 3rd, 1966, and of Ser 1967 b) and the galleries examined in ropalpus sp . (:::;oleoptera : Melandryi this work extended horizontally from dae) between June 29th and Septem one-eighth to one inch inward, then ber 3rd, 1966, and between June usually turned at almost a right-angle 13th and 16th, 1967 (D. A. Ross, and extended vertically for three in litt.). The parasite species Helcon quarters to one inch. Serropalpus sp. idea occidentaZis (Cress.) (Hymenop has round larval entrance holes (D. tera: Braconidae) emerged from May A. Ross, in litt.) and the galleries ex 29th to June 10th, 1966, and Rhim amined extended horizontally into phoctona atrocoxalis (Ashm.) (Hy the wood, curving gently, if at all, and menoptera : Ichneumonidae) from extended for a distance of up to three May 19th to 30th, 1966 (D. A. Ross, in inches, with occasional branching. litt.) . The cocoons from which parasites The log was cut into three-inch had emerged were found only at the 0. 1 mm Figs. 1-2. Final·instar larva of Helconidea occidentalis (Cress.): 1, cephalic structure; 2, spiracle. 64 J. Ewrow)J" Soc. BRIT. COLTn rmA. 66 ('969), AUG. I, 1969 ( ~- - - 3 4 O.l mm O.l mm Figs. 3-4. Final-instar larva of Rhimphoctona atrocoxalis (Ashm.): 3, cephalic structure; 4, spiracle. ends of the Tetropium galleries and in rites in this single preparation were every case were filled with fine wood difficult to determine. Cephalic struc chips or wood powder. None was ture of final-instar larva (Fig. 1) found in the SerropaZpus galleries. lacks epistoma; superior mandibular The cocoons of both parasite species processes are present; inferior mandi contained meconium and final-instar bular processes, pleurostoma and hy larval skins. The methods of prepar postoma are indistinct although ing slides of the final-instar cast showing traces; hypostomal spur en skins and the terminology used are tirely lacking. Stipital sclerite long similar to those described by Finlay and curved with bulbous appendage son (1960). on lateral end; medial end touches labial sclerite on dorsal third. Labial Braconidae sclerite U-shaped with dorsal part of Helconinae: Helconini lateral arms enlarged and slightly H eZconidea occidentaZis (Cress.) twisted. Mandibles with long, slightly (Figs. 1, 2) curved blade with what appears to be The cocoon of this species is about two rows of teeth. Maxillary palpi are 10 mm long by 3 mm wide, buff not visible but the labial palpi are coloured and fairly transparent, and well defined, each with one large and thin, but mica-like In texture. The two or three small sensoria. Antennal large exit hole on the end of the co socket characterized by slightly scle coon is ragged in outline. rotized band with one sensorium. Only one specimen was suitable for Spiracle (Fig. 2) has large atrium study of the cephalic structure and with more or less circular reticula some of the relationships of the scle- tions and opens into stalk with about J. E:'<T() \ IOL. SOl . Bin"!". CO l. D IllIA. 66 (1969) , AJ..:(~. 1, 1969 65 eight narrow annulations and strong trally. Heavy-based hypostomal spur closing a pparatus. Skin densely cov meets stipital sclerite at about mid ered with fine spines and occasional point. Stipital sclerite meets labial short setae. Of those final-instar sclerite at dorsal end of lateral arm. cephalic structures of Braconidae il Labial sclerite with dorsal arms well lustrated in the literature, the cepha sclerotized, each widened medially lic s tructure of Helconidea most and with lateral proj ection ; ventral closely resembles those of the Chelon par t visible but unsclerotized. Prela inae (see e.g. Finlayson 1967, Short bial sclerite Y -shaped. Silk press vis 1952) . ible but unsclerotized. Mandibles each heavy-based with very short blade Ichneumonidae: Porizontinae without teeth meeting base at almost Rhimphoctona atrocoxalis (Ashm. ) a right-angle. Labial and maxillary (Figs. 3, 4) palpi each with one larger and one Cocoon of Rhimphoctona atrocox s maller sensorium. Antennal socket alis (Ashm. ) about 10.5 mm long by visible. Spiracle (Fig. 4) small with 3.2 mm wide; ligh t beige in colour; cup-shaped atrium about 0.012 mm thin and weak but mica-like in tex deep by 0.008 mm wide opening into ture. Remains of final-instar larva closing apparatus a bout 0.014 mm are in meconium at end of cocoon op long and 0.006 mm wide. Skin densely posite exit hole. Exit hole is on tip of covered with very small rounded pro cocoon, jagged in outline, and a bout tuberances and a few small spines. 3.2 mm in diameter. Cephalic structure of final-ins tar Acknowledgments The writer wishes to thank Dr. D. A. larva (Fig. 3) with incomplete epis Ross fo r providing the log from which toma; superior mandibular process known parasites had emerged and for para sclerotized, inferior mandibular pro site and beetle emergence data; Mr. Jim Munro, student assistant, who dissected the cess with two struts, th e posterior one log; and Mr. Derek Parkin who assisted with slightly longer than the anterior; the illustrations. l\ir. G. S. Walley, Entomo pleurostoma unsclerotized. Hypos logy Research Institute, Ottawa, identified the parasites reared from the logs by Dr. toma long and strongly curved ven- Ross. References Finlayson, T. 1960. Taxonomy of cocoons and puparia, and their co ntents, of Canadian parasites of Neodiprion sertifer (Geoff.) (llymenoptera: Diprionidae). Can. Entomol. 92 :20·47 . Finlayson, T. 1967. Taxonomy of final-instar larvae of thE' hymenopterous and dipterous parasites of Acrobasis spp. (Lepidoptera: Phycitidae) in the Ottawa region. Ca n. Entomol. 99 : 1233-1271. Ross, D. A. 1967 a. Wood: and bark-feeding Coleoptera of felled western larch in British Columbia.

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