Predatory Caterpillar (eating insect)

Description:

This caterpillar was about 25 mm long. It had built a silken tube-shaped shelter around it ,with both ends held open by a webbing of silk strands stretching out to the branches of this plant. The caterpillar had a large shiny red head. The body was slender and showed patterns of dark black or blue and white. The caterpillar moved with ease within its shelter and clearly visible were the thoracic legs and about three pairs of prolegs. I spotted a minute insect struggling in the web outside the lower opening of the shelter tube and within a few seconds the caterpillar crawled outside and grabbed the insect with its mandibles (Pic 4). I watched as the whole insect disappear, I assume, into the caterpillar's mouth. Pic 6 shows the entire silk shelter.

Habitat:

Spotted on a prickly acacia (Prickly Moses).

Notes:

A very prickly acacia and a very alert and wary caterpillar made it difficult to get clearer shots. I am looking for an ID for this interesting caterpillar.