The Collaborative International Dictionary of English v.0.48:

Kissing bug \Kiss"ing bug`\ (Zool.)
   Any one of several species of blood-sucking, venomous
   Hemiptera that sometimes bite the lip or other parts of the
   human body, causing painful sores, as the cone-nose
   (Conorhinus sanguisuga). [U. S.]
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

kissing bug
    n 1: large bloodsucking bug [syn: conenose, cone-nosed bug,
         conenose bug, big bedbug, kissing bug]