98  Plants  Used  as  Insecticides.  {^ebSSy,^™' 
gallons  of  water,  and  let  them  soak  one  or  two  days)  and  sprinkled 
with  a  water-pot  over  the  plant,  will,  in  most  cases,  prevent  the 
depredation  of  the  black  grub,  or  cutworm.  (Porcher.) 
Riley  reports  tests  made  by  his  assistants  with  this  plant  as  fol- 
lows : 
"  I  sprayed  a  decoction  of  leaves  and  small  twigs  on  the  cotton 
plants,  and  I  think  it  had  a  large  effect  in  preventnig  the  moths  of 
Heliothis  and  Aletia  from  ovipositing,  but  it  did  not  destroy  the 
larvae.  The  alcoholic  extract  of  the  berries  and  leaves  adulterated 
with  twice  its  quantity  of  water  was  sprayed  on  twelve  Aletia  larvae, 
full-grown;  most  of  them  fell  to  the  ground,  and  four  died.  This 
experiment  was  repeated  with  about  the  same  result ;  but  when  the 
extract  was  diluted  with  ten  parts  of  water  it  failed  to  bring  the 
worms  to  the  ground."    (R.  W.  Jones.) 
"This  plant,  in  the  form  of  alcoholic  extracts  as  well  as  decoc- 
tions, undoubtedly  possesses  some  insecticide  properties,  acting  upon 
the  worms  by  contact,  but  in  a  manner  quite  different  from  pyre- 
thrum  and  kerosene.  The  acting  principle  seems  to  be  of  a  narcotic 
nature,  the  worms  not  showing  any  unusual  disturbance  after  ap- 
plication. They  seem  to  get  benumbed,  and,  gradually  losing  their 
strength,  finally  loosen  their  hold  and  drop  to  the  ground,  where 
they  lie  without  falling  in  convulsions.  The  more  full-grown  worms 
are,  however,  but  little  affected,  and  of  the  smaller  ones  a  large  pro- 
portion recover.  This  is  the  most  promising  plant  of  the  whole 
number  I  experimented  with,  though  the  extracts  and  decoctions  as 
applied  by  myself  are  altogether  too  weak  to  be  used  as  a  remedy 
for  the  worms.  The  preparations  made  from  the  berries  are  evi- 
dently more  effective  than  those  from  the  leaves.  .  .  .  For  further 
experiments  I  would  recommend  preparations  from  the  dried  green 
berries."    (E.  A.  Schwarz.) 
Mentha  Pulegium  L.    Labiatce.    Synonym:  Pulegium  vulgare 
Mill.    European  Pennyroyal,  Flea  Mint.  Europe. 
Serves  as  an  insecticide,    (von  Mueller.) 
Mentha  spicata  L.    Synonyms :  Mentha  spicata  var.  viridis  L. 
1753,  Mentha  viridis  L.  1763  (Kew),  Mentha  sylvestris  var. 
^glabra  Koch.    Spearmint.    Europe,  nat.  in  U.  S.    Leaves  and 
tops  =  Mentha  viridis  U.  S.  P. 
