#398 - Thread-legged Assassin Bug
Reduviid bugs of the subfamily Emesinae, although recent DNA evidence suggests the subfamily needs to be broken up. Noteworthy for their very slender build, and raptorial forelimbs.
Some species, including some common in Australia, prey on spiders, carefully twanging the web to attract the victim. Video here.
This one was on my porch. Possibly it, like all the mantispids I've been getting, was attracted by the spiders. Wellard, Perth