Material and Methods

Whenuapai Airport, outside Auckland, is the chief New Zealand landing-ground for land-based aircraft arriving from abroad. Insects were collected from aircraft reaching this airport, also RNZAF Station, Ohakea, as time and opportunity afforded over the period 1946–48. The results of collections from a total of twenty aircraft were considered in a brief paper read before the Seventh Pacific Science Congress at Christchurch in February, 1949. At the beginning of 1950, the collection of insects from aircraft was assigned as one of the duties of RNZAF mosquito-control personnel at Whenuapai. Since the commencement of World War II, the page 3 RNZAF has assumed responsibility, on behalf of the New Zealand Health Department, for the insecticidal spraying of aircraft arriving at Whenuapai from abroad. Previously, however, it had been impracticable to arrange for regular insect collections to be undertaken in addition to insect control.

RNZAF orderlies search for insects on board aircraft which have arrived at Whenuapai from abroad, following the completion of insecticidal spraying (see page 26) and the subsequent disembarkation of the passengers and crew. The form filled out for each batch of material collected is illustrated below.

Insects Collected on Board Aircraft on Arrival at Whenuapai

IMPORTANT.—In cases where specimens are collected from two or more distinct stations on board the same aircraft, or where both living and dead material is obtained, make out a separate form for each batch of specimens. Use the same reference number for all material from the same aircraft, but differentiate the various batches by using a / sign, e.g., 207/1, 207/2, etc.

The use of the above form has proved most satisfactory in practice, and has allowed of the compilation of more precise data than would have been the case had simple aircraft/occurrence records alone been kept.

All of the twenty aircraft searched by the author in 1946–48 contained insects, a total of 262 specimens being collected. Although 226 aircraft were searched for insects by RNZAF orderlies at Whenuapai during the period February, 1950, to February, 1951, only 295 insects were collected from 68 of these, 158 aircraft being listed as insect-free. This discrepancy is largely explained by the facts that, while the author examined each individual aircraft once only, the Whenuapai orderlies frequently searched one and the same aircraft at the conclusion of numerous distinct flights. While in the early stages of the project accumulations of dead insects which had been on board for lengthy periods were removed from places often overlooked by those responsible for cleaning aircraft—-the basal rim of the astrodome, for example—subsequent examination of the same collecting stations in these aircraft yielded only such insects as had come on board since the previous search. A probable contributory factor with regard to the discrepancy page 4 is that the Whenuapai orderlies had had no previous experience of this kind of work, although the number of tiny and inconspicuous insects which they did discover bears testimony to the care with which they carried out their duties. It is almost inevitable that, even if aircraft insect collections are made by experienced entomologists, many securely hidden specimens will be overlooked. In this connection, Miller et al. (1947) considered that inspectors locate only about 10 per cent. of the insects actually on board aircraft.

Much of the material collected was of a fragmentary and dried-up nature, and had obviously been on board the aircraft concerned for considerable periods. Specific identifications were thus often precluded, although identification to the Family level was possible for all the specimens with the exception of some of the moths. The information derived from the sporadic 1946–48 records has been combined with that derived from the 1950–51 Whenuapai collections in the body of this account.