A degree in anesthesiology?
People often wonder why a biting bed bug doesn’t wake up its human host when it feeds. The answer is components in bed bug saliva act as an anesthetic and promote increased blood flow at the bite site, making feeding quick and nearly painless.
Source: PestWorld.org and Missy Henriksen, vice president of public affairs for the National Pest Management Association (NPMA) and executive director of the Professional Pest Management Alliance (PPMA).
This is one of the greatest myths perpetuated in the bed bug world, there is in fact NO evidence that bed bug saliva contains any anaesthetic properties. A study by Francishetti and colleagues from 2010 (J.Proteom.Res. 9:3820-31) identified 46 different protein components in the saliva of the common bed bug, Cimex lectularius. Many of these proteins are involved in overcoming host haemostatis (i.e. stops the blood clotting while feeding), however no anaesthetic was, or has ever been, identified in the bed bug saliva. Thus why do we not feel the bite? Simply, I suspect, that the stylets of the insects are so fine.
For more discussion on this, see my recent article Doggett et al. 2012. Bed bugs: Clinical relevance and control options. Clinical Microbiological Reviews, 25(1): 164-192.
Stephen Doggett, Director Medical Entomology, Westmead Hospital, Australia &
Principal author of the Code of Practice for the Control of Bed Bugs in Australia.