In Trinidad A. aquasalis swarms over open areas, mostly grass, and over drains and not over scrub vegetation. Swarming commences at a light incidence not exceeding 5 foot,-candles. Mating has been observed in 54 per cent. of the swarms, the fertilisation index of females captured in them being 65 per cent. The lag between the first sight of a swarm and the first observation of a mating pairaverages 6·5 minutes, the light incidence at commencement of mating being no higher than an average of 0·8 foot-candles.
