﻿766 
  

  

  REPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  INSECTS 
  INFESTING 
  THE 
  PEA. 
  

  

  The 
  Pea-Weevil, 
  Bruchus 
  pisi 
  Linn. 
  (Fig. 
  33).— 
  Infesting 
  seed-peas, 
  living 
  in 
  the 
  pea 
  

   its 
  wliole 
  life; 
  a 
  rusty 
  black 
  weevil- 
  like 
  beetle, 
  spotted 
  with 
  lighter 
  shades; 
  a 
  little 
  

   ■over 
  a 
  tenth 
  of 
  an 
  inch 
  long. 
  

  

  The 
  pea-weevil 
  belongs 
  to 
  a 
  small 
  family 
  of 
  beetles 
  called 
  BrucMdce, 
  

   from 
  Bruchus, 
  the 
  name 
  of 
  the 
  principal 
  genus, 
  of 
  which 
  there 
  are 
  300 
  

   species 
  known. 
  They 
  differ 
  from 
  the 
  true 
  weevils 
  in 
  the 
  proboscis 
  being 
  

   folded 
  on 
  the 
  chest, 
  the 
  antennae 
  being 
  short 
  and 
  straight 
  and 
  inserted 
  

   in 
  a 
  cavity 
  next 
  to 
  the 
  eyes. 
  The 
  beetles 
  are 
  short 
  and 
  broad, 
  and 
  are 
  

   noted 
  for 
  their 
  activity 
  and 
  readiness 
  to 
  take 
  flight 
  when 
  disturbed. 
  

   The 
  pea- 
  weevil 
  is 
  oval 
  in 
  form, 
  about 
  an 
  eighth 
  of 
  an 
  inch 
  long, 
  rusty 
  

   black, 
  with 
  a 
  white 
  spot 
  on 
  the 
  hinder 
  part 
  of 
  the 
  prothorax, 
  and 
  four 
  

   or 
  Eve 
  white 
  dots 
  behind 
  the 
  middle 
  of 
  each 
  elytron 
  and 
  a 
  T-shaped 
  

   white 
  spot 
  on 
  the 
  tip 
  of 
  the 
  abdomen. 
  

  

  They 
  frequent 
  the 
  pea 
  during 
  and 
  just 
  after 
  the 
  flowering 
  season. 
  , 
  

   Harris 
  states 
  that 
  " 
  after 
  the 
  pea- 
  vines 
  have 
  flowered, 
  and 
  while 
  the 
  podS; 
  

   are 
  young 
  and 
  tender, 
  and 
  the 
  peas 
  within 
  them 
  are 
  just 
  beginning 
  to^ 
  

   swell, 
  the 
  beetles 
  gather 
  upon 
  them, 
  and 
  deposit 
  their 
  tiny 
  eggs 
  singly 
  

   in 
  the 
  punctures 
  or 
  wounds 
  which 
  they 
  make 
  upon 
  the 
  surface 
  of 
  the 
  

  

  pods." 
  Other 
  authors 
  

   state 
  that 
  with 
  their 
  

   beak 
  they 
  puncture 
  the 
  i 
  

   base 
  of 
  the 
  flower 
  and 
  ' 
  

   lay 
  an 
  egg 
  in 
  the 
  punct- 
  

   /ure. 
  Kiley 
  tells 
  us 
  in 
  ; 
  

   his 
  Third 
  Report 
  (p. 
  47) 
  . 
  

   that 
  " 
  the 
  eggs 
  are 
  deep 
  :; 
  

   yellow, 
  0.035 
  inch 
  long, 
  - 
  

   three 
  times 
  as 
  long 
  as 
  

   wide, 
  fusiform, 
  pointed 
  

  

  Tig. 
  33.— 
  Pea- 
  Weevil, 
  natural 
  size; 
  h, 
  much 
  enlarged; 
  c, 
  jj^ 
  J^^O^*, 
  blunt 
  JDChind, 
  

   larva, 
  natural 
  size 
  and 
  enlarged 
  : 
  d, 
  pupa 
  seen 
  from 
  above, 
  but 
  larger 
  anteriorly 
  

   natural 
  size 
  and 
  enlarged; 
  gf, 
  the 
  beetle 
  coming 
  out 
  of 
  than 
  posteriorly. 
  They 
  -. 
  

   the 
  pea 
  (after 
  Curtis) 
  ; 
  /, 
  egg 
  (after 
  Eiley). 
  ^j,q 
  fastened 
  to 
  the 
  pod 
  

  

  by 
  some 
  viscid 
  fluid 
  which 
  dries 
  white 
  and 
  glistens 
  like 
  silk. 
  As 
  the 
  

   operation 
  of 
  depositing 
  is 
  only 
  occasionally 
  noticed 
  during 
  cloudy 
  { 
  

   weather, 
  we 
  may 
  safely 
  assume 
  that 
  it 
  takes 
  place 
  for 
  the 
  most 
  part 
  by 
  j 
  

   night. 
  If 
  pea-vines 
  are 
  carefully 
  examined 
  in 
  this 
  latitude 
  (Missouri) 
  j 
  

   during 
  the 
  month 
  of 
  June, 
  the 
  "pods 
  will 
  often 
  be 
  found 
  to 
  have 
  from 
  j 
  

   one 
  to 
  fifteen 
  or 
  twenty 
  such 
  eggs 
  upon 
  them, 
  and 
  the 
  black 
  head 
  

   of 
  the 
  future 
  larva 
  may 
  frequently 
  be 
  noticed 
  through 
  the 
  delicate 
  

   shell. 
  * 
  * 
  * 
  * 
  The 
  newly-hatched 
  larva 
  is 
  of 
  a 
  deep 
  yellow 
  color 
  

   with 
  a 
  black 
  head, 
  and 
  it 
  makes 
  a 
  direct 
  cut 
  through 
  the 
  pod 
  into 
  the 
  | 
  

   nearest 
  pea, 
  the 
  hole 
  soon 
  filling 
  up 
  in 
  the 
  pod, 
  and 
  leaving 
  but 
  a 
  mere 
  j 
  

   speck, 
  not 
  so 
  large 
  as 
  a 
  pin-hole, 
  in 
  the 
  pea." 
  The 
  cylindrical, 
  thick, 
  \ 
  

   fleshy 
  grub 
  hatches, 
  and 
  perforates 
  the 
  pod, 
  entering 
  the 
  pea, 
  and 
  there 
  ^ 
  

   lives 
  until 
  it 
  changes 
  to 
  a 
  weevil 
  ; 
  and 
  in 
  stored 
  peas, 
  hibernates 
  within 
  

   them. 
  Their 
  presence 
  in 
  the 
  pea 
  may 
  be 
  detected 
  by 
  a 
  discoloration 
  

   made 
  by 
  the 
  larva 
  within, 
  corresponding 
  to 
  a 
  dark 
  spot 
  on 
  the 
  pea, 
  

   The 
  grub 
  becomes 
  fully 
  grown 
  by 
  the 
  time 
  the 
  pea 
  ripens 
  and 
  dries. 
  It 
  

   then 
  bores 
  around 
  hole 
  from 
  the 
  hollow 
  in 
  the 
  center 
  of 
  the 
  pea, 
  leaving 
  

   the 
  hull 
  and 
  generally 
  the 
  germ 
  untouched 
  ; 
  hence 
  infested 
  peas 
  will 
  

   spring 
  up 
  and 
  grow. 
  The 
  grub 
  changes 
  to 
  a 
  pupa 
  within 
  the 
  pea 
  in 
  the 
  

   autumn, 
  and 
  before 
  the 
  spring 
  casts 
  its 
  skin, 
  becomes 
  a 
  weevil, 
  and 
  

   ^naws 
  a 
  hole 
  through 
  the 
  pea 
  ; 
  it 
  often 
  does 
  not 
  appear 
  until 
  after 
  the 
  

  

  