76 
Hyoscyamus  Niger. 
[Am.  Jour.  Pharm. 
February,  19 19. 
at  the  same  time,  was  not  injurious  to  the  plant.  Paris  green  (i- 
100)  was  too  concentrated  for  hyoscyamus,  as  six  days  after  it  had 
been  applied,  all  three  plants  were  dead,  as  the  result  of  injury  from 
spraying.  Up  to  a  certain  period,  flowers  of  sulphur  proved  fairly 
effective  in  controlling  the  insects.  After  that  time,  they  became 
accustomed  to  the  sulphur,  and  hence,  it  did  not  combat  the  insects. 
The  Colorado  potato  beetle  was  the  most  destructive  insect. 
To  gain  more  information  on  the  effect  of  the  various  sprays  in 
controlling  the  Colorado  beetle,  another  series  of  experiments  was 
carried  out  under  controlled  conditions.  To  each  of  eighteen  sterile 
petri  dishes,  either  one  large  or  two  medium  sized  portions  of  leaves 
of  hyoscyamus  were  added.  The  leaves  of  three  petri  dishes  re- 
ceived no  spray  treatment.  The  leaves  of  three  dishes  were  sprayed 
with  arsenate  of  lead  (5  lbs.  per  100  gal.  of  water)  ;  three,  with 
Paris  green  (1  lb.  per  150  gal.  of  water)  ;  three,  with  Paris  green 
(1  lb.  to  300  gal.  of  water)  ;  and  three,  with  flowers  of  sulphur. 
Into  two  petri  dishes  of  each  series  of  three,  two  potato  beetles  (one 
large  and  one  of  medium  size)  were  placed.  After  24  hours  and 
again  after  70  hours,  the  petri  dishes  and  their  contents  were  care- 
fully examined  and  the  results  recorded. 
As  demonstrated  in  the  preceding  table,  arsenate  of  lead  was  the 
most  satisfactory  in  controlling  the  potato  beetles,  as  it  required  but 
a  small  amount  of  this  poison  to  destroy  these  insects.  Both  dilu- 
tions of  the  Paris  green  were  effective,  but  it  required  a  longer  period 
of  time  to  destroy  the  beetles,  and  a  considerably  larger  amount  of 
the  leaves  were  destroyed  where  the  Paris  green  was  applied,  than 
where  the  arsenate  of  lead  was  employed.  Flowers  of  sulphur  was 
entirely  unsatisfactory,  as  a  means  of  controlling  the  beetles,  as 
shown  on  the  second  examination  (70  hours  after  the  insects  had 
been  in  contact  with  the  leaves),  the  beetles  had  almost  entirely 
destroyed  the  hyoscyamus  leaves,  and  the  bugs  were  still  very  active. 
The  rapidity  with  which  the  beetles  destroy  the  leaves  is  appreciated 
in  the  results  as  shown  in  plates  no.  2  and  no.  3.  In  these  cases 
where  the  leaves  were  not  sprayed,  the  entire  leaves  were  destroyed 
in  24  hours. 
To  ascertain  how  long  Colorado  potato  beetles  could  remain 
alive  when  given  no  food,  six  beetles  (two  large,  two  of  medium 
size  and  two  small)  were  placed  in  a  sterile  petri  dish,  and  their 
activity  was  noted.    The  result  is  shown  in  table  below: 
