The seasons of settlement of shipworms in Tauranga and Wellington harbours in 1970–72 were studied usingPinus radiatatest‐blocks. At Wellington the seasonal abundance of late‐stage shipworm larvae was monitored in the plankton. In Tauranga HarbourBankia australis, Lyrodus medilobatus, Lyrodus pedicellatus, andNototeredoedaxspawned and settled predominantly in summer, when water temperatures were above 17–18°C.Bankia neztaliahad peak periods of settlement in winter and early summer and there was no correlation of settlement with water temperature. In Wellington HarbourB. neztaliaspawned and settled mainly during winter when water temperatures were 11–15°C. Total larval abundance at the 2 test sites in Wellington Harbour was an approximate indication of the relative intensity of settlement, but seasonal larval abundance did not correlate well with seasonal settlement.B. neztalialarvae settled on air‐driedPinus radiatawood within 6 days of the immersion of the wood. Annual variations in patterns of settlement of shipworms in the 2 harbours are related to variations in water temperatures.