Human body lice used to kill more people than all of the bullets and swords
 
 
and bombs combined in wartime. How could such a small insect do so much
 
 
damage? They can spread a germ that causes typhus, a very serious human
 
 
illness that produces a rash, fever, and death. The reason that typhus was so
 
 
bad during wars is that people couldn't wash themselves and their clothes very
 
 
often. If you clean yourself and your belongings, most of the eggs of the lice are
 
 
likely to be removed. Cities that are being attacked by an enemy tend to neglect
 
 
water systems and other services.
 
 
     What changed all of this? In the 1930's Swiss chemists discovered that an
 

entirely new artificial chemical called DDT could kill lice and many other insects
 
 
but be relatively harmless (at first, anyway) to humans. The US and its allies
 
 
dusted the conquered people with DDT and this killed all the lice. Or so everyone
 
 
thought.