Assassin bug (species unidentified) in the Amazon Rainforest, Ecuador. Assassin bugs (Reduviidae) are large predators that suck out the contents of other insects' bodies. Some species feed on the blood of mammals, such as kissing bugs, which bite people's lips while they sleep. Other species harbour the parasite Trypanosoma cruzi, which can kill if transmitted to humans by the bug's bite (Chagas' disease). Assassin bugs are characterised by their flexible neck joint, which makes the small head highly manoeuvrable. Folded out of sight under the head is a long proboscis. A chirping noise is made when teeth on the proboscis are rubbed against the body casing.