Talk in the New Zealand press of mystery aeroplanes and the German threat died down by the beginning of May 1918. At the end of the month, though, mystery aeroplanes returned, followed a few weeks later by the German threat -- albeit both in a more muted fashion.
At Greymouth (on the west coast of the South Island) 'A report was circulated in town last evening [29 May 1918] that an aeroplane had been seen over the sea near the hospital last evening' [sic].1 Unfortunately there are no further details, but on the same night at about the same time, near Hokitika, 40 km to the south,
Several people, including a member of the [Hokitika] 'Guardian' staff, saw in the far roadstead last evening [29 May 1918], a number of vessels just before dusk. A pair of field glasses were obtained and nine vessels were counted. It is also stated that an aeroplane could be seen circling around in near vicinity to the ships. Quite a number gathered on the sea beach to view the interesting sight, but the fast approaching dusk soon hid a further view.2
At neither Greymouth nor Hokitika is any speculation recorded regarding the identity of these aeroplanes or ships.
About three weeks later, a story emerged, not of a new mystery aeroplane sighting, but of one which took place more than a year earlier. There were few details; it was only said that 'in the early part of last year  a Clutha farmer stated that he had seen an aeroplane over the land, and that it had disappeared northwards'.3 This was suggested as 'corroboration to some extent' of reports that the German raider Wolf had sailed right around the New Zealand coast, carrying out aerial reconnaissance of various harbours.4 Further evidence that Wolf had been in southern waters at the time came from the crew of a trawler, who saw a light which they took to be another vessel (which turned out to be back in port), and local Māori, who saw searchlights playing over Stewart Island, again presumed to be from a ship (no government steamers were so equipped).5 This belated report prompted G. H. Lysnar to inform the Poverty Bay Herald and 'the authorities at Wellington' that 'in March or April last year  [...] he saw the aeroplane or seaplane [...] from his station a few miles beyond Parikanapa, and it was travelling from Poverty Bay in the direction of between Mohaka and Wairoa':
Mr Lysnar says he regrets not having reported the occurrence at the time, but there then was no talk or thought of a raider with a seaplane visiting New Zealand, and he came to the conclusion at the time it was one of the flying machines from the Auckland Flying School paying a visit to either Napier or Wellington, and which preferred taking the coast line so as to be over cleared country; otherwise in the event of engine trouble it might have had to land in the back ranges in the bush.6
It's an interesting index of how much more probable a German aeroplane visit now seemed, that Lysnar felt compelled to give an elaborate explanation of why he hadn't thought to report what he had seen.