Large numbers of Xenopsylla vexabilis hawaiiensis were needed to carry out tests of its efficiency as a plague vector. Efficient culture of the Hawaiian flea was accomplished in white enameled buckets containing a housed host rat together with a larval substrate consisting of sand and powdered dog pellets (Friskies). The pupae were kept at a temperature of from 23° to 27°C. and a relative humidity of from 93 per cent to 100 per cent. These conditions differed from those required by Xenopsylla cheopis, which was maintained separately at lower temperature and humidity. The pupae were sifted from the sand approximately every 3 weeks for maximum production.
In nature, X. v. hawaiiensis was found to breed in rat nests which consisted mainly of dried grass leaves. This evidence, together with the results of laboratory culture, suggests that the fleas probably do not breed on the surface of the ground, nor do the larvae require green grass as formerly postulated.