﻿U. 
  S. 
  D. 
  A., 
  B 
  . 
  E. 
  Bui. 
  116, 
  Part 
  I. 
  D. 
  F. 
  1. 
  1., 
  Issued 
  July 
  15, 
  1912. 
  

  

  PAPERS 
  ON 
  DECIDUOUS 
  FRUIT 
  INSECTS 
  AND 
  INSECTICIDES. 
  

  

  SPRAYING 
  EXPERIMENTS 
  AGAINST 
  THE 
  GRAPE 
  LEAFHOP- 
  

   PER 
  IN 
  THE 
  LAKE 
  ERIE 
  VALLEY 
  IN 
  191 
  1, 
  

  

  By 
  Fred 
  Johnson, 
  

   Agent 
  and 
  Expert. 
  

  

  INTRODUCTION. 
  

  

  An 
  insect 
  pest 
  of 
  the 
  grapevine 
  which 
  has 
  increased 
  in 
  abundance 
  

   and 
  destruetiveness 
  in 
  the 
  vineyards 
  of 
  the 
  Lake 
  Erie 
  Valley 
  during 
  

   the 
  past 
  few 
  years 
  is 
  the 
  grape 
  leafhopper, 
  

   Typhlocyoa 
  comes 
  Say 
  (see 
  fig. 
  1). 
  Pre- 
  

   liminary 
  spraying 
  experiments 
  were 
  under- 
  

   taken 
  against 
  this 
  pest 
  at 
  North 
  East, 
  Pa., 
  

   by 
  the 
  Bureau 
  of 
  Entomology 
  in 
  1910. 
  

   Results 
  of 
  the 
  field 
  work 
  undertaken 
  during 
  

   that 
  season 
  are 
  presented 
  in 
  Bulletin 
  No. 
  

   97, 
  Part 
  I, 
  of 
  the 
  Bureau 
  of 
  Entomology, 
  

   together 
  with 
  a 
  brief 
  consideration 
  of 
  the 
  

   characteristics, 
  habits, 
  and 
  life 
  history 
  of 
  

   the 
  insect, 
  and 
  also 
  the 
  character 
  and 
  ex- 
  

   tent 
  of 
  its 
  injury 
  to 
  the 
  vine. 
  For 
  this 
  

   reason 
  the 
  subject 
  matter 
  of 
  this 
  paper 
  

   deals 
  entirely 
  with 
  experiments 
  conducted 
  

   during 
  the 
  season 
  of 
  1911. 
  Readers 
  un- 
  

   familiar 
  witli 
  the 
  habits 
  of 
  this 
  pest 
  should 
  

   consult 
  the 
  paper 
  referred 
  to 
  above. 
  

  

  Fig. 
  1.— 
  The 
  grape 
  leafhopper 
  

   (Typhlocyba 
  coma 
  var. 
  colo- 
  

   radensis): 
  Adult. 
  Greatly 
  en- 
  

   larged. 
  (Author's 
  illustration.) 
  

  

  TREATMENT 
  OF 
  NYMPHS 
  OF 
  THE 
  GRAPE 
  LEAFHOPPER 
  WITH 
  

   CONTACT 
  SPRAYS. 
  

  

  During 
  the 
  season 
  of 
  1911 
  the 
  grape 
  leafhopper 
  was 
  more 
  numerous 
  

   and 
  destructive 
  to 
  the 
  grapevines 
  in 
  the 
  vineyards 
  of 
  Erie 
  County. 
  

   Pa., 
  than 
  in 
  1910. 
  Owing, 
  doubtless, 
  to 
  the 
  higher 
  temperatures 
  

   prevailing 
  during 
  June 
  and 
  July 
  of 
  this 
  season, 
  the 
  nymphs 
  (see 
  fig. 
  2) 
  

   commenced 
  to 
  appear 
  on 
  the 
  leaves 
  at 
  an 
  earlier 
  date, 
  and 
  the 
  develop- 
  

   ment 
  of 
  the 
  nymphaJ 
  singes 
  of 
  the 
  insect 
  were 
  more 
  rapid 
  than 
  in 
  1910. 
  

   Since 
  it 
  is 
  in 
  this 
  the 
  nymphal 
  period 
  before 
  the 
  insect 
  has 
  developed 
  

  

  