io6  insects  Destructive  to  Books.        f  Am.  jour.  Pharm. 
(  j^ovemoer,  1911. 
Company,  of  Philadelphia,  called  my  attention  to  the  fact,  that  the 
working  clothes  of  the  employees  of  his  company,  if  left  hanging  in 
a  dark  place  for  a  time,  were  found  to  have  been  gnawed  by  the 
larva  of  some  species  of  insect,  and  that  the  most  striking  part  was, 
only  that  part  of  the  clothing  which  had  been  stained  with  ink  was 
eaten.  Most  inks  contain  one  or  more  acids  in  their  composition, 
and  as  they  are  claimed  to  be  poisonous  and  therefore  should  kill, 
one  would  say  that  the  parts  of  the  goods  discolored  by  the  inks 
should  be  exempt  from  these  attacks,  instead  of  proving  attractive. 
A  French  author  writes  of  a  book  in  which  the  insects  had  eaten  the 
portion  of  the  paper  which  had  received  the  impress  of  the  ink, 
showing  that  they  were  after  something  besides  the  paper,  paste  or 
binding. 
To  prove  this,  I  took  a  piece  of  parchment — sheepskin  and  imi- 
tation— and  a  quantity  of  the  finest  grade  of  engraver's  black  print- 
ing ink,  made  a  circle  of  ink  in  the  centre  with  diagonal  lines  run- 
ning from  this  to  the  corners  and  sides  and  a  one-eighth  inch  border 
all  around  the  edges.  After  the  ink  was  dry,  I  placed  a  piece  of  each 
kind  of  parchment  in  a  tin  can  with  twelve  roaches,  adding  water 
from  time  to  time  for  drinking  purposes.  At  the  end  of  two  weeks 
an  examination  of  the  parchment  showed  that  the  roaches  had  eaten 
all  of  the  edges,  had  then  followed  the  diagonal  lines,  eating  mostly 
the  portions  so  marked,  and  then  the  circle,  showing  that  they  knew 
the  value  to  them  of  the  acetic  acid  which  was  in  the  ink. 
I  hope  that  other  experiments  will  be  made  along  the  same  lines 
to  ascertain  if  the  various  dyes,  though  often  of  the  same  color, 
are  more  secure  from  the  inroads  of  insects  than  others,  on  account 
of  containing  certain  chemicals  in  their  composition.  Blatta  orien- 
talis  was  the  species  used  in  making  these  experiments. 
CONDITIONS  FAVORABLE  FOR  THE  PROPAGATION  OF  BOOK  PESTS. 
Darkness. — The  majority  of  libraries  generally  keep  a  large  num- 
ber of  their  books  upon  stacks  placed  in  a  dark  portion  of  the  build- 
ing, badly  ventilated,  and  the  only  light  available  as  a  rule  is  from 
gas  jets  or  incandescent  lamps,  which  are  only  lighted  when  needed. 
This  darkness  (the  necessary  condition  for  the  starting  of  all  life), 
the  more  or  less  damp  air  which  is  found  in  these  surroundings, 
the  gases  of  various  kinds  in  the  air,  and  the  fact  that  the  books 
most  seldom  called  for  are  kept  in  these  locations,  all  combine  to  give 
