Am.  Jour.  Pharm.  1 
November,  1911.  j" 
Insects  Destructive  to  Books. 
513 
Books  as  Disease  Carriers. — Again,  I  speak  upon  the  transmis- 
sion of  diseases  by  books,  because  the  greatest  disease  carrier  among 
insects  that  we  know  of  to-day  is  the  common  house-fly,  Musca 
domestica,  which  is  also  one  of  the  book-destroying  insects.  There 
are  a  number  of  instances  where  the  maggots  of  the  fly  have  been 
found  Hving  upon  paper,  kept  in  damp  places,  but  the  damage  done 
directly  to  the  book  is  as  nothing  when  compared  to  the  damage 
done  by  their  transferring  germs,  and,  unless  means  are  taken  foi 
their  extermination,  they  will  rank  first  among  book  enemies,  because 
those  who  know  of  the  fly's  ability  to  carry  disease  germs,  will  refuse 
to  read  any  book  which  the  fly  has  stained.  The  common  house-fly 
is  only  found  around  the  habitation  of  man,  showing  that  it  has 
evolved  from  some  other  form  which  formerly  lived  in  the  open 
until  it  has  now  become  thoroughly  domesticated,  as  other  forms 
have  done,  are  doing,  and  will  do  in  the  future. 
According  to  Dr.  Howard,  a  single  female  fly  in  the  spring 
might,  therefore,  become  the  progenitor  of  195,312,500,000,000,000 
flies  by  the  end  of  the  summer  or  mid-autumn,  and  allowing  one 
million  flies  to  a  bushel  makes  ovef  193  million  bushels,  each  one  of 
whom  is  capable  of  spreading  contagion.  An  investigation  made  at 
the  Agricultural  Experiment  Station  at  Storrs,  Connecticut,  in  1908, 
upon  414  flies,  showed  that  the  number  of  bacteria  on  a  single  fly 
may  range  all  the  way  from  550  to  6,600,000,  an  average  of  one 
and  one-fourth  millions  bacteria  on  each,  an  almost  incredible 
number  to  be  found  on  such  a  small  object.  The  objectionable  class, 
coli-aerogenes  type,  was  two  and  one-half  times  as  abundant  as 
the  favorable  acid  type.  Now  this  only  includes  those  on  the  outside, 
and  every  bacteriologist  knows  that  large  numbers  are  found  in 
the  intestines  and  expelled  with  the  excreta.  Mr.  N.  A.  Cobb,  in 
his  article  "  The  House-Fly,"  ^  states  that  a  well-fed  fly  defecates 
T04  times  in  less  than  two  hours,  and  that  spores  were  found  in  fifty- 
five  of  the  specks.  These  specks,  containing  germs,  are  laid  upon 
the  covers  or  pages  of  the  books,  and  as  personal  observation  shows 
that  a  very  large  portion  of  readers  moisten  their  fingers  in  turning- 
over  the  leaves  of  a  book,  it  is  readily  seen  how  the  fly  speck  upon 
the  paper  is  moistened,  adheres  to  the  finger  and  the  germs  trans- 
planted to  the  mouth,  where  they  at  once  find  the  proper  conditions 
and  proceed  to  breed,  resulting  in  the  reader  becoming  afflicted  with 
^  f^ational  Geographic  Magazine,  vol.  xxi,  1910,  pp.  37i~38o, 
