SOME HUMAN PARASITES 279 



BED BUGS 



The common bed bug, Cimex lectularius (fig. 79, B), has 

 been recognised in this country for over four hundred 

 years, although, like the common cockroach, it is an in- 

 troduced species. Well known to the Romans, by whom 

 it was considered to possess medicinal properties, as a 

 specific against snake bites, the " wall louse," to give it its 

 old English name, was apparently introduced into Great 

 Britain about the year 1503. Like many other domestic 

 insects, the bed bug has followed in the wake of man all 

 over the world. 



Usually associated with dirt, this insect does not scorn 

 clean dwellings, especially if there is a reasonable chance 

 of obtaining a meal of human blood. The bed bug is 

 popularly and scientifically so called on account of its habit 

 of visiting beds and attacking their inmates. Abandoning 

 beds by day, it hides in masses, in cracks, beneath paper, 

 etc., a habit in which it is aided by the extreme flatness of 

 its body. In its efforts to escape observation during the 

 hours of light, it evinces a very remarkable degree of 

 intelligence. It is commonly supposed that the demise of 

 the old wooden four-poster and the substitution of metal 

 bedsteads sounded the death-knell of this loathsome little 

 animal. It has, however, been found hiding in the crevices 

 of iron bedsteads, and the general improvement in domestic 

 cleanliness of the present day is probably the reason why 

 it is less common now than formerly. As is the case with 

 all insects that have assumed a wholly or partially parasitic 

 habit, the bed bug exhibits considerable structural degrada- 

 tion. Its normal food is human blood, and, as this is 

 always partaken of at night, there is little need for active 

 locomotion, so that the insect, unlike the majority of bugs, 

 is wingless, or, to be more correct, the wings are represented 

 by a pair of pads, quite useless for flight. It is fortunate 

 perhaps that there are no wings, for, bad enough pest as 



