- Johnson, N. E., K. H. Wright, and P. W. Orr. 1961. Attack and brood survival by the Douglas-fir beetle (Dendroctonus pseudotsugae) in four types of windthrown trees in western Washington. 13 p..
- Ragenovich, I. R., and H. D. Brown. 1980. Southwestern Region (R-3). Pp. 20-24. in: Forest Insect and Disease Conditions in the United Sates 1978. Orr, P. W. (eds.) United States Department of Agriculture, Forest Service. iv+83 pp..
- Buckhorn, W. J., and P. W. Orr. 1958. Forest insect conditions in the Pacific Northwest during 1958. United States Department of Agriculture, Forest Service, Pacific Northwest Forest and Forest Range Experiment Station, p. 14-22.
- Buckhorn, W. J., and P. W. Orr. 1959. Forest insect conditions in the Pacific Northwest during 1959. Pages 12-20. United States Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station.
- Buckhorn, W. J., and P. W. Orr. 1961. Forest insect conditions in the Pacific Northwest during 1960. United States Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 42 p.
- Buckhorn, W. J., and P. W. Orr. 1962. Forest insect conditions in the Pacific Northwest during 1961. United States Department of Agriculture, Forest Service, Insect and Disease Control Branch, Division of Timber Management, Pacific Northwest Region. 41 p.
- Furniss, M. M., and P. W. Orr. 1970. Douglas-fir beetle (Dendroctonus pseudotsugae). United States Department of Agriculture, Forest Service, Forest Pest Leaflet 5 (revised). 4 p.
- Graham, S. A., and L. W. Orr. 1940. The spruce budworm in Minnesota. Minnesota Agricultural Experiment Station, Technical Bulletin 142.
- Hanson, J. B., W. H. Hoffard, and P. W. Orr. 1977. Northeastern States (R-9). Pages 48-54 in H. V. Toko and K. H. Knauer, Forest insect and disease conditions in the United States, 1975. United States Department of Agriculture, Forest Service. vi + 60 p.
- Johnson, N. E., P. W. Orr, and K. H. Wright. 1959. Beetle hazard in windthrown Douglas-fir. Weyerhaeuser Company, Forestry Research Center, Forestry Research Note 20. 3 p.
- Leach, J. G., L. W. Orr, and C. Christensen. 1934. The interrelationships of bark beetles and blue-staining fungi in felled Norway pine timber. Journal of Agricultural Research 49:315-341, figs. 1-13.
- Leach, J. G., L. W. Orr, and C. Christensen. 1937. Further studies on the interrelationship of insects and fungi in the deterioration of felled Norway pine logs [Scolytidae, p 129, 130, 139] . Journal of Agricultural Research 55:129-140.
- Lindgren, B. S., J. H. Borden, L. Chong, L. M. Friskie, and D. B. Orr. 1983. Factors influencing the efficiency of pheromone-baited traps for three species of ambrosia beetles (Coleoptera: Scolytidae) . Canadian Entomologist 115:303-313.
- Orr, J. J. 1942. Reducing pine beetle damage through partial cutting . West Coast Lumberman 6942, 44, 46, 79.
- Orr, L. W. 1925. A correction in the recorded hibernation habits of two species of Ips bark beetles in Minnesota . Journal of Economic Entomology 28:1021-1022.
- Orr, L. W. 1933. Bark beetle control in Minnesota . Smoke Screen 9:1-3.
- Orr, L. W. 1937. Recent developments affecting bark beetle control in Minnesota (Ips pini and Ips grandicollis) . Minnesota Agricultural Experiment Station, Report for 1936:29.
- Orr, L. W. 1954. The role of surveys in forest-insect control . Journal of Forestry 52:250-252.
- Orr, L. W., and R. J. Kowal. 1956. Progress in forest entomology in the South . Journal of Forestry 54:653-656.
- Orr, L. W., and R. R. Lara. 1967. 57. Southern pine beetle. Dendroctonus frontalis Zimm. (=arizonicus Hopk. and mexicanus Hopk). Pages 213-216 in A. G. Davidson and R. M. Prentice (eds.), Important forest insects and diseases of mutual concern to Canada, the United States and Mexico. Canada Department of Forestry and Rural Development, Publication 1180. Ottawa, Canada. 248 p.
- Orr, P. W. 1956. Forest insect surveys, Mount Hood National Forest and adjacent timber lands, 1946-1955. United States Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, Oregon. 9 p.
- Orr, P. W. 1963a. Forest insect conditions in the Pacific Northwest during 1962. United States Department of Agriculture, Forest Service, Insect and Disease Control Branch, Division of Timber Management, Pacific Northwest Region, Portland, Oregon. 47 p.
- Orr, P. W. 1963b. Oregon and Washington. Pages 3-6 in J. W. Bongberg, Forest insect and disease conditions in the United States, 1962. United States Department of Agriculture, Forest Service. 30 p.
- Orr, P. W. 1966. Oregon and Washington. Pages 7-12 in J. W. Bongberg, Forest insect and disease conditions in the United States, 1965. United States Department of Agriculture, Forest Service. 47 p.
- Orr, P. W., and L. F. Pettinger. 1964. Forest insect conditions in the Pacific Northwest during 1963. United States Department of Agriculture, Forest Service, Insect and Disease Control Branch, Division of Timber Management, Pacific Northwest Region, Portland, Oregon. 60 p.
- Orr, P. W., L. F. Pettinger, and R. E. Dolph. 1965. Forest insect conditions in the Pacific Northwest during 1964. United States Department of Agriculture, Forest Service, Pacific Northwest Region, Portland, Oregon. 90 p.
- Orr, P. W., L. F. Pettinger, and R. E. Dolph. 1966. Forest insect conditions in the Pacific Northwest during 1965. United States Department of Agriculture, Forest Service, Insect and Disease Control Branch, Division of Timber Management, Pacific Northwest Region, Portland, Oregon. 70 p.
- Orr, T. J. 1942. Reducing pine beetle damage through partial cutting . West Coast Lumberman 6942, 44, 46, 79.
- Orr, T. J. 1945. Selective marking in ponderosa pine on a Klamath Falls tree farm . Journal of Forestry 43:738-741.
- Wear, J. F., R. B. Pope, and P. W. Orr. 1966. Aerial photographic techniques for estimating damage by insects in western forests (in the United States). United States Department of Agriculture, Forest Service, Pacific Northwest Forest Range Experiment Station, Portland, Oregon. 4 col., (2+) 79 p., 8 figs.
- Wyckoff, S. N., C. Hartley, and L. W. Orr. 1947. Protection against forest insects and diseases in the United States. United States Department of Agriculture, Forest Service, Reappraisal of the Forest Situation, No. 5 (processed report). 39 p.