﻿390 
  

  

  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  192 
  9 
  

  

  rarious 
  forms 
  that 
  appear 
  to 
  be 
  representative 
  of 
  several 
  other 
  

   modern 
  orders 
  of 
  wing-folding 
  insects. 
  The 
  roaches 
  at 
  least 
  were 
  

   inhabitants 
  of 
  the 
  forests, 
  adapted 
  to 
  living 
  in 
  the 
  matted 
  vegeta- 
  

   tional 
  debris 
  of 
  the 
  forest 
  floor, 
  on 
  the 
  scaly-barked 
  trees, 
  or 
  between 
  

   the 
  bases 
  of 
  their 
  frondlike 
  leaves. 
  

  

  The 
  dragon 
  flies 
  belong 
  to 
  the 
  order 
  Odonata, 
  but 
  there 
  are 
  two 
  

   distinct 
  suborders 
  of 
  them. 
  One 
  suborder, 
  known 
  as 
  the 
  Anisoptera, 
  

   includes 
  the 
  ordinary 
  large 
  species, 
  or 
  true 
  dragon 
  flies 
  (fig. 
  7), 
  which, 
  

   when 
  at 
  rest, 
  keep 
  the 
  wings 
  spread 
  straight 
  out 
  at 
  the 
  sides 
  of 
  the 
  body. 
  

   The 
  other 
  suborder 
  is 
  the 
  Zygoptera 
  and 
  includes 
  species 
  generally 
  

   smaller 
  in 
  size 
  which, 
  when 
  at 
  rest, 
  fold 
  the 
  wings 
  over 
  the 
  back 
  with 
  

  

  #^^^- 
  ^,.-. 
  " 
  ,.j 
  g 
  

  

  

  Figure 
  7.— 
  Dragon 
  flies 
  of 
  the 
  suborder 
  Anisoptera. 
  When 
  the 
  insects 
  are 
  perched 
  the 
  wings 
  are 
  

   held 
  horizontally 
  at 
  right 
  angles 
  to 
  the 
  body 
  

  

  the 
  dorsal 
  surfaces 
  together. 
  (Fig. 
  8.) 
  Members 
  of 
  the 
  Zygoptera 
  

   are 
  sometimes 
  distinguished 
  as 
  damsel 
  flies; 
  most 
  of 
  them 
  are 
  rather 
  

   weak 
  creatures 
  with 
  long, 
  slim 
  abdomens 
  and 
  slender 
  wings 
  narrowed 
  

   at 
  the 
  bases. 
  They 
  are 
  comparatively 
  feeble 
  fliers 
  and 
  are 
  easily 
  

   caught. 
  The 
  true 
  dragon 
  flies 
  of 
  the 
  suborder 
  Anisoptera 
  are 
  sub- 
  

   divided 
  into 
  two 
  families, 
  the 
  Libellulidae 
  and 
  the 
  Aeschnidae. 
  The 
  

   libellulids 
  are 
  the 
  common 
  dragon 
  flies 
  seen 
  about 
  streams 
  and 
  pools, 
  

   where 
  they 
  perch 
  on 
  the 
  ends 
  of 
  twigs 
  from 
  which 
  they 
  dart 
  out 
  on 
  

   vigorous 
  short 
  flights 
  in 
  pursuit 
  of 
  some 
  small 
  passing 
  insect. 
  The 
  

   aeschnids 
  include 
  those 
  large 
  species 
  that 
  we 
  used 
  to 
  call 
  Devil's 
  

   darning 
  needles. 
  Thej^ 
  are 
  most 
  efficient 
  fliers, 
  being 
  seldom 
  seen 
  to 
  

   .alight 
  anywhere 
  as 
  they 
  go 
  skimming 
  above 
  the 
  surface 
  of 
  the 
  water. 
  

  

  