﻿32 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  los 
  

  

  their 
  appearance, 
  time 
  of 
  occurrence, 
  and 
  favored 
  habitats. 
  It 
  is 
  note- 
  

   worthy 
  that 
  on 
  a 
  single 
  day, 
  September 
  12, 
  1950, 
  Dr. 
  Townes 
  and 
  his 
  

   associates 
  found 
  two 
  larvae, 
  one 
  on 
  Hapithus^ 
  the 
  other 
  on 
  Orocharis. 
  

   Specimens 
  belonging 
  to 
  the 
  University 
  of 
  Michigan 
  show 
  that 
  on 
  three 
  

   other 
  occasions, 
  once 
  in 
  Indiana 
  and 
  twice 
  in 
  Florida, 
  a 
  collector 
  has 
  

   found 
  two 
  instances 
  of 
  parasitism 
  in 
  a 
  single 
  day. 
  

  

  There 
  remain 
  many 
  unanswered 
  questions 
  concerning 
  the 
  biology 
  

   of 
  the 
  species 
  of 
  Rhopalosoma, 
  some 
  of 
  which 
  may 
  require 
  controlled 
  

   cage 
  studies. 
  Stages 
  earlier 
  than 
  the 
  fourth 
  instar 
  are 
  still 
  known 
  

   from 
  exuviae 
  and 
  fragments 
  of 
  eggshell, 
  and 
  first 
  instar 
  specimens 
  

   are 
  especially 
  desirable 
  for 
  morphological 
  study. 
  

  

  More 
  study 
  material, 
  including 
  specimens 
  from 
  northern 
  and 
  south- 
  

   ern 
  States, 
  may 
  show 
  that 
  more 
  than 
  one 
  form 
  of 
  Rho'palosoma 
  occurs 
  

   in 
  the 
  United 
  States. 
  Adults 
  of 
  nearcticum 
  were 
  distinguished 
  from 
  

   their 
  Neotropical 
  congeners 
  by 
  Brues 
  (1943) 
  on 
  rather 
  minor 
  morpho- 
  

   logical 
  features, 
  and 
  differences 
  correlated 
  with 
  geographic 
  distribu- 
  

   tion 
  might 
  be 
  better 
  represented 
  in 
  larvae 
  than 
  adults. 
  Of 
  the 
  four 
  

   fifth-instar 
  specimens 
  examined, 
  the 
  ones 
  from 
  Georgia 
  and 
  North 
  

   Carolina 
  and 
  the 
  exuviae 
  of 
  Hood's 
  Maryland 
  specimen 
  lack 
  teeth 
  on 
  

   the 
  mandibles, 
  while 
  the 
  larva 
  from 
  Virginia 
  apparently 
  has 
  a 
  full 
  

   complement 
  of 
  teeth 
  on 
  the 
  left 
  mandible 
  but 
  only 
  a 
  few 
  basal 
  ones 
  on 
  

   the 
  right 
  mandible. 
  It 
  is 
  not 
  known 
  whether 
  occasional 
  breakage 
  of 
  

   teeth 
  occurs 
  while 
  the 
  larvae 
  are 
  burrowing 
  in 
  soil 
  prior 
  to 
  cocoon 
  

   formation. 
  Some 
  breakage 
  of 
  the 
  teeth 
  of 
  the 
  Virginia 
  larva 
  may 
  

   have 
  resulted 
  from 
  my 
  manipulation 
  of 
  the 
  mandibles 
  with 
  needles 
  

   before 
  I 
  realized 
  the 
  existence 
  of 
  teeth. 
  The 
  three 
  fifth-stage 
  larvae 
  

   have 
  been 
  measured 
  for 
  maximum 
  head 
  width 
  and 
  length 
  of 
  mandibles. 
  

   The 
  ratio 
  of 
  head 
  width 
  to 
  length 
  of 
  mandible 
  is 
  1.68, 
  1.86, 
  and 
  2.0 
  for 
  

   the 
  larvae 
  from 
  Virginia, 
  North 
  Carolina, 
  and 
  Georgia, 
  respectively. 
  

  

  Brief 
  examination 
  of 
  a 
  few 
  examples 
  of 
  other 
  families 
  has 
  sug- 
  

   gested 
  certain 
  characters 
  which 
  deserve 
  careful 
  attention 
  in 
  subse- 
  

   quent 
  work 
  of 
  a 
  comparative 
  nature. 
  A 
  chrysidid 
  larva 
  {Ghrysis) 
  

   has 
  the 
  second 
  thoracic 
  spiracle 
  located 
  behind 
  the 
  groove 
  separating 
  

   meso- 
  and 
  metathorax, 
  while 
  the 
  corresponding 
  spiracle 
  of 
  Rhopalo- 
  

   soma 
  is 
  slightly 
  in 
  front 
  of 
  the 
  groove. 
  Unlike 
  the 
  condition 
  in 
  

   Rhopalosoma^ 
  the 
  second 
  spiracle 
  of 
  a 
  tiphiid 
  larva 
  (Oosila) 
  is 
  smaller 
  

   than 
  adjacent 
  ones. 
  This 
  tiphiid 
  larva 
  has 
  two 
  maxillary 
  appendages, 
  

   and 
  there 
  are 
  two 
  prominent 
  angular 
  projections 
  on 
  the 
  labium 
  in 
  the 
  

   area 
  of 
  the 
  sericteries. 
  As 
  more 
  details 
  of 
  rhopalosomatid 
  life 
  histories 
  

   become 
  available, 
  comparisons 
  with 
  the 
  situation 
  in 
  the 
  Tiphiidae, 
  

   such 
  as 
  has 
  been 
  discussed 
  by 
  Clausen, 
  King, 
  and 
  Teranishi 
  (1927), 
  

   will 
  perhaps 
  be 
  instructive. 
  

  

  A 
  larva 
  of 
  one 
  of 
  the 
  Larridae 
  {Larra 
  analis 
  Fabricius, 
  which 
  at- 
  

   tacks 
  mole 
  crickets) 
  has 
  the 
  head 
  proportionately 
  smaller 
  than 
  

  

  