9 /l/rMDNTANA DEPARTMENT OF NATURAL ^RESOURCES AND CONSERVATION DIVISION OF FORESTRY . ' 11 : C- ' INSECT AND DISEASE REPORT Missoula, Montana 59 801 Report 77-2 Montana State Library 3 0864 1006 4787 7 942.41 February 1977 DOUGLASFIR TUSSOCK MOTH DETECTION SURVEY USING PHEROMONE-BAITED STICKY TRAPS - 1976 By Steve Kohler, Entomologist Cooperative Forest Management Division of Forestry SUMMARY In 1975, pheromone-baited sticky traps were placed at 125 locations throughout the host range of Douglasfir tussock moth, Orgyia pseu- dotsugata (McDunnough) , in western Montana. Male moths were caught at 69 of these locations, but none were caught east of the Continental Divide. In 19 76, traps with stronger baits were placed at 43 loca- tions, chiefly east of the Continental Divide. Douglasfir tussock moth males were caught at only two locations east of the Divide. Both sites were in the Wolf Creek area north of Helena. INTRODUCTION In work done in 1975, pheromone-baited sticky traps were placed at 125 locations throughout the entire host range (Douglasfir and spruce- true fir types) of Douglasfir tussock moth, Orgyia pseudotsugata (McDunnough) , which included the western half of the State (Kohler, 1976) . Male Douglasfir tussock moths were caught at 69 of the 125 total locations. Although approximately 30 of the locations were east of the continental Divide, no moths were taken there. Results of the trapping showed the principal distribution of Douglasfir tus- sock moth in Montana to be the northwest portion of the State (Figure 1) . This included the Flathead Valley, the Swan Valley, the Clark Fork drainage from Rock Creek (east of Missoula) to Idaho, the Black- foot River drainage east from Missoula to Greenough, and the Bitter- root Valley south to Darby. Since there are large areas of relatively pure Douglasfir stands east of the Continental Divide in Montana, providing abundant host material, it was expected that Douglasfir tussock moth should occur in at least some of these areas. To verify this suspicion, and also to refine the known distribution of Douglasfir tussock moth in Montana, traps were placed at 43 locations in 1976. Most of the trapping locations east of the Continental Divide from the 1975 survey were repeated, and some new locations added. METHOD Traps used in the survey were again the Pherocon-2 Insect Trap, manu- factured by Zoecon Corporation, Palo Alto, California. The traps are a white paper fold-out type with sticky coating on the inside. The assembled trap forms a square-shaped sleeve six inches long and three inches on each side. Trap placement began August 5, 1976. All traps were in the field by August 31, 1976. Trap retrieval began October 1, 1976, and was com- pleted October 29, 1976. In the field, the traps were positioned on open-grown Douglasfir at least ten feet tall. They were fastened with wire ties to the outer branches of the lower tree crowns where they could be reached from the ground. Care was taken that trap entrances were not obscured by branches, providing for easy access by moths. Two traps were placed at each location on separate trees at least 100 feet apart. Baits for the traps were provided by the U. S. Department of Agricul- ture, Forest Service, Pacific Northwest Forest & Range Experiment Station, Corvallis, Oregon. They consisted of pieces one centimeter square, cut from a sheet of mylar plastic coated with a plastic resin containing the pheromone, (2)-6-heneicosen-ll-one (Smith, et al . , 1975) Concentration of the pheromone was higher than either of the bait types used in the 1975 survey. The mylar plastic bait squares were suspended inside the trap on the tip of a pin pushed through the side of the trap. - 2 - 1975 SURVEY douglas-f ir tussock moth present o douglas-fir tussock moth absent Figure 1 - 3 - After retrieval, the traps were stored on end and transported to the laboratory. This prevented the traps from collapsing and damaging the trapped insects, thereby making identification more difficult. In the laboratory, the traps were cut open for examination, and numbers of Douglasfir tussock moth and other tussock moths recorded. RESULTS Douglasfir tussock moth males were caught at eight of the 43 loca- tions of the 1976 survey. Of these locations, six were west of the Continental Divide, and two were east of the Continental Divide (Figure 2). East of the Divide, Douglasfir tussock moth males were trapped at a location in the Wolf Creek State Forest, and at another location south of Wolf Creek. Four different species of tussock moths were caught in the traps in 1976. They were: Douglasfir tussock moth, Orgy i a pseudotsugata (McDunnough) ; western tussock moth, 0. cana (Edwards) ; rusty tussock moth, 0. antiqua (Linnaeus) ; and Dasychira vagans grisea (Barnes & McDunnough) . Location of trapping sites, number and species of tussock moths caught, are given in the following table. - 4 - Table 1. Location of pheromone-baited sticky trap sites in Montana and number of adult male tussock moths trapped at each site in 1976. Plot No. Location T. R. S. Aspect Elevation Trap Tree Species Nunfoer of Tussock Moths Trapped 0. pseudotsugata 0. carta O, antigua D. vagans 45 Highwood Mountains 19N 9E 22 SW 5150 DF 66 Lone Tree Creek 16N 9E 25 NW 4900 DF 70 Monarch 16N 7E 34 Flat 4620 DF 79 Gold Creek 14N 16W 32 S 3750 DF 80 East Belmont Creek 14n lew 24 NW 3950 DF 81 Ovando 14N 13W 2 E Xct "C. 4400 DF 82 Arrastra Creek 14N 10W 28 s 4270 DF 88 Holter Dam 13N 2W 4 N 4200 DF 89 Judith River 12N HE 12 SW 4900 DF 94 Cramer Creek 12N 16W 36 W 5500 DF 95 Bear Gulch 11N 14W 3 E 5450 DF 96 Rattler Gulch 12N 13W 36 E 5720 DF 97 Green Pole Creek 13N 17E 25 E 4820 DF 100 Hoover Creek ION 11W 3 E 5240 DF 101 Davis Creek UN 9W 16 NE 5300 DF 102 Marysville 12N 5W 32 SE 5400 DF 103 Miller Gulch UN 7E 8 SE 5500 DF 105 Little Blackfoot River ION 8W 3 N 4785 DF 106 Avalanch Creek ION IE 11 NW 4250 DF 109 Jefferson City 7M 3W 16 N 4800 DF 110 Grassy Mountain 7N 5E 34 E 6000 DF 112 Divide Creek 2N 9W 32 E 5900 DF 113 S, Fork Big Timber Creek 3N 13E 16 N 6040 DF 114 Mink Creek IN 18W 6 NW 5420 DF 1.15 Piquett Creek IN 21W 3 E 5040 DF 116 Bridger Mountains IN 7E 4 E 5650 DF 117 Cherry Creek. 2S 14E 9 NW 5900 DF 118 Pine Creek 4S 10E 7 NW 5550 DF 120 Birch Creek 5S 10W 15 W 6200 DF 121 Big Creek 6S 7E 18 SW 5500 DF 124 Blackball Creek 9S 8W 16 N 6820 DF 125 Little Sheep Creek 14S 9W 36 E 6800 DF 126 Wolf Creek 15N 4W 30 N 4650 DF 127 S. of Wolf Creek 14N 4W 22 W 4590 DF 128 Ross Gulch 7N 4E 32 NE 5200 DF 129 Potter Creek 13N 2IE 16 N 4900 DF 130 Burley Peak UN 11E 5 NW 5800 DF 131 Spring Creek ION 10E 29 N 5020 DF 132 Big Creek 6S 7E 13 E 5200 DF 133 Bear Canyon 2S 7E 30 N 5010 DF 134 Big Hole River IN 10W 32 S 5860 DF 135 Divide IS 9W 7 N 5920 DF 87 Helmville 13N 12W 15 E 4300 DF 0 0 1 0 0 0 17 0 0 0 54 0 38 0 10 2 18 0 2 1 0 0 25 1 0 0 18 J 0 0 0 0 0 0 2 0 18 0 4 0 1 0 7 1 0 0 0 0 0 0 37 0 0 0 1 0 0 0 6 1 0 0 15 0 0 0 4 0 0 0 ' 4 0 0 47 0 0 0 0 18 2 0 0 2 0 0 0 u 0 0 0 J 0 3 0 9 0 6 4 12 0 0 0 41 0 0 0 3 1 0 0 10 0 0 2 1 0 0 0 2 0 0 2 4 0 0 1 0 0 1 0 1 0 1 0 2 0 0 11 2 0 0 0 64 0 0 0 13 0 0 0 0 0 0 0 0 0 0 0 64 0 0 0 1 0 0 0 0 0 0 0 9 0 Figure 2 REFERENCES Kohler, S= 1976. Douglasfir tussock moth detection survey using pheromone-baited sticky traps. Montana Department of Natural Resources & Conservation, Division of Forestry, Insect & Disease Report 76-2. Smith, R.G., G.E. Daterman, and G.D. Daves, Jr. 1975. Douglasfir tussock moth: Sex pheromone identification and synthesis. Science 188; 63-64. Work leading to this report was funded in part by a U. S. Department of Agriculture sponsored program titled, "Expanded Douglasfir Tussock Moth Research and Development Program" . 7 -