The assasin bugs are a large family of Heteroptera that are most diverse in the tropical regions of the world. They range in size from a couple of millimeters long up to nearly 40 millimeters in length. In Australia the Reduviidae is the only family found in the superfamily Reduvioidea.
Most reduvids are predators of other invertebrates though a few species feed on the blood of vertebrates. Some species have the fore legs modified, often with spines or specialised areas of hair that act as an adhesive, to grasp and hold the prey while they feed. Many are ambush predators, using visual clues to locate prey while remaining concealed or camoflauged against the background. The nymphs of some Reduviidae cover themselves with debris from the environment using specialised secretions in order to better blend into the substrate or vegetation.
Unlike some other predatory families of Heteroptera that are timid in their approach and taking of prey, for example the Anthocoridae, some of the larger reduvids can be aggressive and will readily attempt to take prey larger than themselves. These species will also give the unwary collector a nasty bite if handled incorrectly or carelessly.
A few of the species of rediviids in the subfamily Emesinae are recorded as living in the webs of spiders where it has been variously reported that they are predators of the spiders themselves or opportunistic feeders on the prey captured by the spider. With their raptorial fore legs and long mid and hind legs they bear a passing resemblance to preying mantids and may be mistaken for such by novices.
Reduviidae is one of the few families of Heteroptera known to transmit disease to humans. In Central and South America reduviids of the subfamily Triatominae can transmit Chagas' disease to humans that they have been feeding upon. Unlike diseases transmitted by mosquitos, Chagas' disease is transmitted through the insects contaminated faeces coming into contact with the open wound created by the bite, and not through the insects mouthparts or saliva acting as a conduit into the body.
Stridulation (sound production) has been recorded from both adult and nymphal Reduviidae. The sound is produced by the rubbing of the apex of the rostrum in a striated groove located on the prosternum. It is generally regarded as a defensive mechanism though other sounds not related to defence have been recorded.