My estimation of 5 billion is for the full number flying at night between the Queensland border and the Snowy Mountains, since the density is so great they are showing up on the BOM radar. It is only a very very rough estimate based on my 5 minute observation at a single location
This caterpillar made it to adulthood, but was unfortunately dead when I found it. The adult moth is shown in sighting 4718940 (Psychidae (family) MATURE (Case Moth)) as found.