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imported  species,  but  all  those  of  indigenous  species  and  of  species 
and  families  related  to  the  indigenous  ones. 
Everything  possible  must  be  tried  with  the  confidence  that  in 
some  case  the  best  results  might  be  obtained. 
I have  said  before  that  it  is  necessary  to  know  the  biology  of 
indigenous  parasites  in  order  to  appreciate  as  much  as  possible 
those  which  are  most  useful  for  the  natural  fight  and  in  order  to 
also  multiply  them  when  possible,  but  having  to  deal  with  forms 
which  in  our  country  have  numerous  inimical  causes,  we  may 
perhaps  never  succeed  in  limiting  these,  if  at  all  only  very  par- 
tially, while  by  introducing  and  acclimating  a foreign  primary 
parasite  without  his  secondary  parasite  or  parasites,  we  can  obtain 
a continuous  and  very  effective  natural  fight  against  certain  in- 
sects. 
Among  the  species  of  insects  of  foreign  origin  we  must  seek  to 
fight  by  the  introduction  of  their  parasites  Diaspis  pentagona  Tar., 
Lepidosaphes  citricola  Pack.,  Parlatoria  zizyphi  Luc.,  Aonidiella 
cmrantii  Mask.,  Schizoneara  lanigera  Hausm.  The  olive-fly  is 
probably  also  of  foreign  origin,  but  even  if  such  be  not  the  case, 
I insist  just  the  same  in  defending  the  attempt  of  the  natural 
method  to  fight  it  by  introducing  its  enemies  which  probably  exist 
in  Asia  and  Africa,  and  the  enemies  of  the  other  species  of  Dacus, 
which  live  principally  in  India. 
The  natural  fight  must  always  be  tried  with  the  greatest  con- 
fidence  and  since  it  required  only  one  expense  during  the  studies 
and  necessary  researches  for  one  or  a few  years,  while  its  result 
may  be  the  best  and  continuous,  it  must  be  abandoned  only  after 
all  possible  trials  have  failed. 
In  order  to  be  able  to  apply  the  natural  fight  the  most  pro- 
found biological  knowledge  of  the  insects  to  be  fought  and  of 
their  parasites  is  necessary  because  the  cases  in  which  matters  are 
quite  simple  as  in  the  case  of  Icerya  and  of  Novius  are  few ; there- 
fore the  institution  of  a large  entomological  section  near  the 
Ministry  of  Agriculture  is  more  than  ever  necessary. 
For  the  introduction  of  parasites  from  abroad  I believe  the 
International  Institute  of  Agriculture  can  be  relied  upon  to  a great 
extent,  when  the  entomological  section  will  be  well  organized 
there,  but  at  all  events  it  will  be  always  necessary  to  have  also  in 
Italy  a traveling  entomologist,  who  has  acquired  a knowledge  of 
foreign  injurious  insects  and  of  their  parasites  in  the  countries 
which  they  inhabit,  in  order  to  be  able  to  select  on  a solid  scientific 
basis  the  species  necessary  for  the  fight  against  indigenous  insects 
or  those  imported  in  Italy. 
One  other  fact  to  which  I believe  it  is  timely  to  call  the  attention 
of  farmers  is  the  great  danger  which  always  threatens  our  indus- 
tries and  which  lies  in  the  possible  easy  introduction  of  some 
foreign  injurious  insect.  The  Diaspis  of  the  mulberry  tree  for 
instance. 
