﻿— 
  114 
  — 
  

  

  The 
  eggs 
  of 
  insects 
  of 
  this 
  family 
  are 
  laid 
  either 
  upon 
  the 
  leaves 
  of 
  

   the 
  plant 
  infested 
  by 
  the 
  larvae 
  or 
  on 
  its 
  roots 
  or 
  in 
  the 
  ground 
  close 
  by. 
  

   The 
  root-feeding 
  larvae 
  are 
  usually 
  whitish 
  and 
  slender, 
  but 
  the 
  leaf-eat- 
  

   ing 
  species 
  are 
  darker, 
  shorter, 
  and 
  thicker, 
  and 
  often 
  with 
  the 
  segments 
  

   strongly 
  marked. 
  The 
  larvae 
  change 
  to 
  whitish 
  pupae 
  in 
  the 
  earth, 
  about 
  

   the 
  base 
  of 
  the 
  plant 
  infested 
  by 
  them. 
  As 
  a 
  general 
  rule 
  the 
  species 
  

   pass 
  the 
  winter 
  as 
  adults, 
  are 
  found 
  feeding 
  on 
  the 
  leaves 
  in 
  May, 
  

   and 
  produce 
  larvce 
  in 
  June, 
  adults 
  from 
  which 
  are 
  present 
  in 
  July 
  and 
  

   August. 
  Two 
  and 
  even 
  three 
  broods 
  may 
  occur 
  before 
  the 
  end 
  of 
  the 
  

   season, 
  but 
  in 
  many 
  root-feeding 
  forms 
  there 
  is 
  but 
  one 
  each 
  year. 
  The 
  

   important 
  genus 
  Systoia 
  forms 
  a 
  notable 
  exception 
  to 
  the 
  foregoing 
  

   account, 
  hibernating 
  either 
  as 
  larva 
  or 
  egg, 
  and 
  producing 
  a 
  single 
  

   brood 
  of 
  adults 
  in 
  summer. 
  Colaspis 
  seems 
  to 
  have 
  a 
  similar 
  history 
  to 
  

   Sysiena, 
  and 
  Chcvtocnema 
  departs 
  from 
  that 
  given 
  above 
  by 
  the 
  fact 
  that 
  

   its 
  single 
  brood 
  of 
  larvae 
  appears 
  about 
  a 
  month 
  later. 
  

  

  The 
  greater 
  part 
  of 
  the 
  beet 
  leaf-beetles 
  belong 
  to 
  the 
  group 
  com- 
  

   monly 
  known 
  as 
  flea-beetles 
  because 
  of 
  the 
  expert 
  quickness 
  and 
  energy 
  

   with 
  which 
  they 
  leap 
  when 
  disturbed. 
  This 
  group 
  can 
  be 
  distinguished 
  

   from 
  other 
  beetles 
  of 
  the 
  family 
  by 
  the 
  very 
  thick 
  hind 
  thighs, 
  shaped 
  

   somewhat 
  like 
  those 
  of 
  a 
  grasshopper. 
  Other 
  members 
  of 
  this 
  family 
  

   fly 
  rather 
  than 
  leap 
  when 
  alarmed, 
  their 
  hind 
  thighs 
  being 
  of 
  ordinary 
  

   size. 
  The 
  species 
  of 
  flea-beetles 
  infesting 
  the 
  beet 
  are 
  so 
  numerous, 
  the 
  

   individuals 
  so 
  small, 
  and 
  the 
  characters 
  distinguishing 
  them 
  so 
  technical 
  

   and 
  obscure, 
  that 
  a 
  discrimination 
  of 
  the 
  species 
  — 
  useless 
  as 
  it 
  is 
  for 
  

   economic 
  purposes 
  — 
  will 
  not 
  be 
  attempted 
  in 
  this 
  paper. 
  The 
  entomolo- 
  

   gist 
  interested 
  in 
  specific 
  characters 
  is 
  referred 
  to 
  Dr. 
  Horn's 
  "Synopsis 
  

   of 
  the 
  Halticini 
  of 
  Boreal 
  America."* 
  Certain 
  of 
  these 
  jumping 
  beetles 
  

   are, 
  however, 
  so 
  common 
  and 
  occasionally 
  destructive 
  in 
  the 
  beet 
  field 
  

   that 
  they 
  are 
  deserving 
  of 
  special 
  mention. 
  

  

  The 
  yellow-black 
  flea-beetle 
  {Disonycha 
  xa*iiho?nelcena 
  — 
  PI. 
  V., 
  VI.) 
  

   is 
  one 
  of 
  the 
  commoner 
  beet 
  insects, 
  both 
  larva 
  and 
  adult 
  feeding 
  upon 
  

   the 
  leaves. 
  It 
  may 
  be 
  distinguished 
  among 
  the 
  flea-beetles 
  by 
  its 
  com- 
  

   paratively 
  large 
  size 
  (its 
  length 
  about 
  a 
  quarter 
  of 
  an 
  inch), 
  by 
  its 
  

   metallic 
  greenish-blue 
  or 
  black 
  head 
  and 
  wing-covers, 
  with 
  the 
  thorax 
  

   uniform 
  pale 
  yellowish 
  above 
  and 
  black 
  beneath 
  and 
  the 
  abdomen 
  

   entirely 
  yellow 
  beneath. 
  A 
  much 
  smaller, 
  also 
  very 
  abundant, 
  species 
  

   whose 
  injuries 
  in 
  spring 
  frequently 
  attract 
  attention, 
  is 
  the 
  pale-striped 
  

   flea-beetle 
  {Syste/ia 
  tceniata 
  — 
  Fig. 
  39). 
  This 
  is 
  about 
  an 
  eighth 
  of 
  an 
  

   inch 
  in 
  length, 
  light 
  yellowish 
  brown 
  in 
  general 
  color, 
  with 
  a 
  broad 
  pale 
  

   stripe 
  down 
  each 
  wing-cover. 
  f 
  

  

  *Trans. 
  Am. 
  Ent. 
  Soc, 
  Vol. 
  XVI. 
  (1889), 
  pp. 
  163-320. 
  

  

  rOther 
  species 
  which 
  have 
  been 
  found 
  on 
  beets, 
  many 
  of 
  them 
  more 
  or 
  less 
  injurious, 
  are 
  Dtsonchya 
  

   crinicollis, 
  D. 
  triangularis, 
  and 
  D. 
  cerziicalis, 
  Systena 
  hitdsonias 
  and 
  S. 
  frontalis, 
  Phyllotreta 
  vittata, 
  

   P. 
  albionica, 
  and 
  P. 
  deci/'iens, 
  Epitrix 
  brevis, 
  Crepidodera 
  airiventris, 
  Glyptina 
  brunnea, 
  Longitarsus 
  

   tnelanurus, 
  Chietocnema 
  detiticulata, 
  C. 
  pitlicaria, 
  and 
  C. 
  confinis, 
  and 
  Psylliodes 
  punctitlata 
  and 
  P, 
  

   convexior. 
  

  

  