Am.  Jour.  Pharm.  ) 
May,  1879.  j 
Insect  Powder. 
^45 
More  recently  we  have  been  experimenting  with  this  powder  on  the 
green  Aphis  which  troubles  our  green-house  plants.  The  usual  plan  of 
smoking  with  tobacco  is  an  unpleasant  remedy,  and  is  also  very  injurious 
to  many  plants  of  delicate  constitution,  whereas  the  insect  powder  used 
to  any  extent  is  perfectly  harmless  to  plant-life.  After  freely  charging 
the  air  of  a  green  house  with  the  powder,  blowing  it  in  fine  clouds  of 
dust  among  the  plants,  the  tiny  tormentors  who  are  busily  engaged  in 
sucking  the  life  out  of  the  leaves  and  tender  shoots,  soon  manifest 
symptoms  of  uneasiness  and  begin  to  drop  from  the  plants  to  the  ground, 
and  in  the  course  of  an  hour  or  two  the  larger  portion  of  the  enemy's 
forces  will  be  found  lying  sprawling  on  the  earth  in  the  pots  or  on  the 
shelves  and  floor  of  the  house,  where,  probably  partly  from  the  stupe- 
fying effects  of  the  powder  and  partly  from  their  natural  inability  to  find 
their  way  to  any  given  point,  they  fail  to  reach  the  plants  again  and 
hence  perish.  By  applying  the  powder  freely  in  the  evening  and  giving 
the  plants  a  thorough  syringing  in  the  morning,  they  may  in  the  worst 
cases  be  almost  freed  from  Aphides  by  a  single  application;  it  is  better, 
however,  to  repeat  its  use  the  next  evening,  so  as  to  make  sure  work. 
The  powder  does  not  appear  to  kill  this  Aphis  as  it  does  the  flies.  For 
the  purpose  of  testing  this  point  we  placed  a  number  of  them  in  an 
open  glass  cell  of  a  microscope  slide  and  powdered  them  thoroughly, 
and  found  some  of  them  alive  after  two  days  of  such  severe  exposure 
to  its  influence.  Having  recently  found  a  plant  literally  swarming  with 
the  green  Aphis,  so  that  the  sight  of  it  was  almost  disgusting,  we  sub- 
mitted it  to  the  action  of  this  powder  one  afternoon,  having  previously 
spread  a  large  piece  of  white  paper  under  the  plant  so  that  the  effect  of 
the  powder  on  the  insects  might  be  distinctly  seen.  Almost  immediately 
they  began  to  fall  on  the  paper,  and  in  less  than  ten  minutes  a  hundred 
or  more  of  them  were  lying  on  their  backs  or  crawling  sluggishly  about. 
In  the  course  of  half  an  hour  some  four  or  five  hundred  had  fallen  on 
the  paper,  and  when  the  plant  was  examined  again  the  following  morn- 
ing, there  remained  but  very  few  on  it,  and  most  of  these  were  removed 
by  a  slight  syringing.  We  have  had  the  powder  used  in  green-houses 
by  some  of  our  friends,  who  also  report  its  success.  The  matter  is 
well  worthy  the  attention  of  all  those  who  indulge  in  window  gardening 
or  who  grow  plants  in  small  conservatories  attached  to  dwellings,  since 
if  this  proves  an  efficient  and  economical  substitute  for  tobacco  smoke, 
it  will  save  much  annoyance  and  some  loss.    Success  will  necessarily 
