- Milligan, R. H. 1969a. An introduced ambrosia beetle (Xyleborus saxeseni) attacking logs and freshly sawn timber. 4 p,.
- Milligan, R. H. 1969b. Beech insects. 58-59.
- Milligan, R. H. 1973a. Forest entomology Xyleborus truncatus. 59-60.
- Milligan, R. H. 1969c. Insect damage to eucalypts . New Zealand Forest Service, Forest Research Institute, Report 1968:60.
- Milligan, R. H. 1970a. Biology of indigenous Platypus species . New Zealand Forest Service, Forest Research Institute, Report 1969:61-62.
- Milligan, R. H. 1970b. Overseas wood- and bark-boring insects intercepted at New Zealand ports. New Zealand Forest Service, Forest Research Institute, Technical Paper 57. 80 p.
- Milligan, R. H. 1972. A review of beech forest pathology . New Zealand Journal of Forestry 17:201-211.
- Milligan, R. H. 1973b. Forest entomology: Platypus damage in relation to beech (Nothofagus) management . New Zealand Forest Service, Forest Research Institute, Report 1973:58-59.
- Milligan, R. H. 1974. Insects damaging beech (Nothofagus) forests . New Zealand Ecological Society, Proceedings 21:32-40.
- Milligan, R. H. 1978. Hylastes ater (Paykull) (Coleoptera: Scolytidae). Black pine bark beetle. New Zealand Forest Service, Forest and Timber Research Institute, Forest and Timber Insects in New Zealand 29. 8 p. (unpaginated).
- Milligan, R. H. 1979. Platypus apicalis White and Platypus caviceps Broun (Coleoptera: Platypodidae). The native pinhole borers. Forest and Timber Insects in New Zealand 37. 16 p.
- Milligan, R. H. 1982a. Evidence for an aggregating pheromone in Platypus apicalis (Coleoptera: Platypodidae). Pages 37-50 in R. A. Galbreath (ed.), Insect pheromones and their application. Proceedings of a workshop held at Mount Albert Research Centre, Auckland, New Zealand, 10-12 February 1981.
- Milligan, R. H. 1982b. Platypus pinhole borer (Platypus apicalis) affects sprinklers storage of logs in New Zealand . New Zealand Journal of Forestry 27:236-253.
- Milligan, R. H., G. O. Osborne, and G. Ytsma. 1988. Evidence for an aggregation pheromone in Platypus gracilis Broun (Col, Platypodidae) . Journal of Applied Entomology 106:20-24.
- Milligan, R. H., and G. Ytsma. 1988. Pheromone dissemination by male Platypus apicalis White and P. gracilis Broun (Col., Platypodidae). Journal of Applied Entomology 106: 113-118.