﻿The 
  Rkd-headed 
  Flea-beetle. 
  

  

  Sysiena 
  frontalis 
  Fabr. 
  

  

  (PI. 
  VIII., 
  Fig. 
  2.) 
  

  

  A 
  somewhat 
  elongate 
  insect, 
  about 
  an 
  eighth 
  of 
  an 
  inch 
  long, 
  with 
  

   a 
  narrow 
  thorax, 
  resembling 
  the 
  preceding 
  species 
  in 
  form 
  and 
  general 
  

   appearance, 
  and 
  bluish 
  black 
  like 
  that, 
  except 
  that 
  the 
  head 
  is 
  pale 
  red- 
  

   dish. 
  It 
  has 
  been 
  reported 
  from 
  New 
  York 
  as 
  riddling 
  the 
  leaves 
  of 
  

   garden 
  beets 
  to 
  an 
  extent 
  to 
  give 
  the 
  field 
  a 
  brownish 
  look. 
  It 
  has 
  also 
  

   been 
  seen 
  in 
  moderate 
  numbers 
  on 
  beets 
  in 
  Illinois 
  and 
  Nebraska. 
  

   Other 
  cultivated 
  plants 
  are 
  occasionally 
  infested, 
  unusual 
  injury 
  having 
  

   been 
  reported 
  to 
  the 
  leaves 
  of 
  the 
  gooseberry, 
  grape, 
  and 
  pear. 
  It 
  is 
  

   especially 
  a 
  smartweed 
  beetle, 
  but 
  feeds 
  also 
  on 
  lamb's-quarters 
  and 
  on 
  

   one 
  of 
  the 
  mallows 
  (^Hibiscus 
  militarist. 
  It 
  seems 
  to 
  be 
  most 
  abundant 
  

   in 
  August 
  and 
  September, 
  but 
  its 
  life 
  history 
  is 
  unknown. 
  In 
  the 
  single 
  

   instance 
  of 
  reported 
  injury 
  the 
  attack 
  was 
  arrested 
  by 
  spraying 
  with 
  

   Paris 
  green. 
  

  

  The 
  Pale-striped 
  Flea-beetle. 
  

  

  Systena 
  tccniata 
  Melsh. 
  

  

  (ySystena 
  blanda 
  Say. 
  ) 
  

  

  This 
  is 
  one 
  of 
  the 
  most 
  abundant 
  and 
  generally 
  injurious 
  of 
  the 
  

   flea-beetles 
  and 
  infests 
  an 
  unusual 
  variety 
  of 
  plants, 
  most 
  of 
  them 
  

  

  abundant 
  weeds. 
  It 
  is 
  very 
  destructive 
  in 
  

   beet 
  fields 
  especially 
  when 
  unseasonable 
  

   weather 
  prevents 
  an 
  early 
  and 
  rapid 
  growth 
  

   of 
  the 
  plant. 
  In 
  1899, 
  for 
  example, 
  sugar- 
  

   beet 
  planting 
  was 
  largely 
  delayed 
  in 
  Illinois 
  

   until 
  the 
  middle 
  or 
  latter 
  part 
  of 
  May. 
  To- 
  

   wards 
  the 
  middle 
  of 
  June, 
  when 
  these 
  later 
  

   plantings 
  were 
  very 
  small, 
  the 
  adults 
  of 
  this 
  

   species 
  were 
  emerging 
  in 
  great 
  numbers 
  and, 
  

   concentrating 
  on 
  the 
  young 
  beets, 
  com- 
  

   pletely 
  destroyed 
  many 
  fields 
  of 
  this 
  plant, 
  

   Fig. 
  39. 
  The 
  Pale-striped 
  Flea- 
  necessitating 
  a 
  second 
  and 
  sometimes 
  a 
  third 
  

  

  beetle, 
  Systena 
  twniata, 
  adult. 
  

  

  planting. 
  Ihe 
  beetles 
  commonly 
  do 
  not 
  eat 
  

   quite 
  through 
  the 
  leaf 
  of 
  the 
  beet, 
  but 
  gnaw 
  pit-like 
  excavations 
  on 
  both 
  

   surfaces 
  until 
  young 
  plants 
  if 
  severely 
  infested 
  blacken, 
  shrivel 
  up, 
  and 
  

   disappear, 
  whole 
  fields 
  being 
  thus 
  laid 
  completely 
  bare. 
  If 
  the 
  plant 
  

   survives, 
  the 
  epidermis 
  of 
  the 
  leaf 
  opposite 
  to 
  the 
  injury 
  dries 
  up 
  and 
  

   breaks 
  away, 
  a 
  small 
  hole 
  thus 
  resulting. 
  This 
  injury 
  was 
  much 
  great- 
  

   est, 
  according 
  to 
  our 
  observation, 
  on 
  beets 
  following 
  or 
  adjoining 
  clover 
  

   sod. 
  The 
  principal 
  damage 
  to 
  beets 
  by 
  this 
  insect 
  was 
  done 
  the 
  third 
  

  

  