Am'jmier'i9isarm'  }   Vegetable  Powder  as  a  Larvicide.  447 
An  export  tax  of  30  pesetas  will  be  levied  on  each  100  kilos  net. 
All  exports  are  subject  to  control  and  licenses  are  revocable  at  any 
time  by  the  national  commission  on  supplies.  (Peseta,  par  value, 
$0,193;  kilo,  2.2  pounds.) 
[The  embargo  on  olive  oil  of  all  grades  was  announced  by  the 
Spanish  government  on  September  7,  191 7.  An  export  duty  of  40 
pesetas  per  100  kilos  was  imposed.] 
This  Spanish  decree,  permitting  export  of  olive  oil  under  certain 
regulations,  will  serve  to  relieve  to  a  moderate  degree  only  the 
shortage  of  this  prime  necessity  in  the  American  market.  The  em- 
bargoes on  the  export  of  Italian  and  French  olive  oils,  which  have 
heretofore  largely  supplied  the  United  States,  have  created  an  acute 
condition  regarding  supplies  of  olive  oil,  both  edible  and  technical 
grades.  The  home  production,  largely  in  California,  has  developed 
some  excellent  grades  of  oil,  but  is  as  yet  capable  of  supplying  but 
a  very  small  percentage  of  the  needs  of  the  country  for  this  product. 
As  a  consequence  olive  oil  of  all  grades  has  advanced  to  prices  that 
were  not  thought  possible. 
VEGETABLE  POWDER  AS  A  LARVICIDE  IN  THE  FIGHT 
AGAINST  MOSQUITOES.1 
A  Preliminary  Note. 
By  James  K.  Thibault,  Jr.  (Washington,  D.  C), 
Bureau  of  Entomology,  United  States  Department  of  Agriculture, 
Scott,  Ark. 
With  the  view  to  finding  some  larvicide  cheaper  than  crude  oil 
and  just  as  effective,  and  at  the  same  time  available  for  use  in  cer- 
tain places  that  can  be  neither  oiled  nor  drained,  such  as  water 
gardens,  outdoor  fish  pools,  rice  fields  and  the  like,  I  have  experi- 
mented with  many  substances  during  the  past  few  years.  I  have 
found  not  the  perfect  larvicide  I  sought,  but  one  that  meets  at  least 
a  few  of  the  requirements  of  perfection,  and  that  I  consider  well 
worth  a  trial  by  those  engaged  in  the  work  of  exterminating  mos- 
quitoes. While  not  a  substitute  for  oil  under  all  conditions,  it  is 
certainly  much  cheaper  than  oil,  as  easy  of  application  and,  in 
1  From  the  Journal  of  the  American  Medical  Association,  April  27,  1918. 
