﻿734 
  EEPORT 
  UNITED 
  STATES 
  GEOLOGICAL 
  SURVEY. 
  

  

  1 
  

  

  I 
  append 
  the 
  following 
  account 
  of 
  several 
  potato-insects 
  of 
  Europe, 
  

   taken 
  from 
  Curtis's 
  Farm 
  Insects, 
  and 
  which 
  may 
  prove 
  of 
  interest, 
  since 
  

   the 
  same 
  or 
  closely-allied 
  species 
  are 
  likely 
  to 
  occur 
  m 
  the 
  United 
  

   States 
  I 
  

  

  "Dead 
  and 
  silent 
  as 
  the 
  earth 
  appears 
  to 
  be, 
  it 
  teems 
  with 
  life 
  ; 
  for 
  not 
  

   only 
  is 
  the 
  soil 
  full 
  of 
  seeds, 
  which 
  merely 
  require 
  light 
  and 
  heat 
  to 
  

   start 
  them 
  into 
  life, 
  but 
  it 
  must 
  abound 
  with 
  the 
  eggs 
  of 
  insects 
  so 
  mi- 
  

   nute 
  that 
  even 
  with 
  the 
  assistance 
  of 
  a 
  lens 
  they 
  escape 
  one's 
  notice. 
  To 
  

   be 
  convinced 
  of 
  the 
  truth 
  of 
  this, 
  if 
  a 
  flower-pot 
  be 
  filled 
  with 
  mold 
  

   from 
  a 
  field 
  or 
  garden, 
  and 
  then 
  tied 
  over 
  with 
  the 
  finest 
  muslin, 
  the 
  

   experimentalist 
  will 
  be 
  astonished 
  to 
  find 
  the 
  multitudes 
  of 
  little 
  flies 
  

   which 
  are 
  constantly 
  making 
  their 
  appearance, 
  bred 
  no 
  doubt 
  from 
  larva?,, 
  

   nourished 
  on 
  the 
  vegetable 
  matter 
  which 
  such 
  soils 
  contain. 
  Where 
  

   crops 
  are 
  grown, 
  and 
  any 
  portion 
  of 
  them 
  become 
  decayed, 
  the 
  num- 
  

   ber 
  of 
  these 
  minute 
  insects 
  is 
  vastly 
  multiplied, 
  and 
  thus 
  where 
  the 
  

   deceased 
  potatoes 
  have 
  existed 
  additional 
  swarnss 
  of 
  various 
  little 
  flies 
  

   have 
  been 
  the 
  consequence. 
  As 
  a 
  proof 
  of 
  the 
  incredible 
  numbers 
  that 
  

   must 
  be 
  thus 
  generated, 
  I 
  may 
  mention 
  that 
  from 
  one 
  growing 
  and 
  par- 
  

   tially-rotten 
  potato 
  I 
  bred 
  in 
  August, 
  1845, 
  128 
  flies, 
  independent 
  ot 
  

   many 
  more 
  which 
  had 
  died 
  in 
  the 
  pupa 
  state, 
  or 
  been 
  destroyed 
  by 
  damp 
  

   and 
  mites 
  before 
  I 
  discovered 
  them 
  in 
  the 
  vessel 
  in 
  which 
  the 
  tuber 
  was 
  

   placed, 
  as 
  well 
  as 
  multitudes 
  of 
  smaller 
  flies, 
  all 
  of 
  which 
  I 
  will 
  now 
  

  

  "The 
  "whole 
  belong 
  to 
  the 
  order 
  Diptera. 
  The 
  first 
  I 
  shall 
  notice 
  is 
  

   included 
  in 
  the 
  family 
  Tipulid^ 
  and 
  the 
  genus 
  Psijchoda 
  and 
  has 
  

   been 
  named 
  — 
  

  

  " 
  P. 
  nervosa.— 
  The 
  males 
  are 
  twice 
  as 
  large 
  as 
  the 
  females 
  ; 
  they 
  are 
  ashy-white, 
  

   clothed 
  with 
  longish 
  wool 
  ; 
  the 
  little 
  head 
  is 
  buried 
  under 
  the 
  thorax 
  ; 
  the 
  black 
  eyes 
  

   are 
  laro-e 
  and 
  Innatas 
  ; 
  the 
  two 
  horns 
  are 
  as 
  long 
  as 
  the 
  thorax, 
  and 
  composed 
  ot 
  eleven 
  ( 
  I 
  ) 
  

   small 
  points, 
  black 
  at 
  the 
  base, 
  giving 
  them 
  an 
  annulated 
  appearance 
  ; 
  the 
  abdomen 
  

   is 
  short, 
  and 
  of 
  a 
  dirty 
  color 
  ; 
  the 
  two 
  wings 
  when 
  at 
  rest 
  meet 
  over 
  the 
  back 
  slant- 
  

   ing; 
  they 
  are 
  iridescent, 
  very 
  large, 
  oval, 
  and 
  lanceolate, 
  with 
  numerous 
  longitudinal, 
  

   hairv 
  nervures 
  ; 
  the 
  entire 
  margin 
  is 
  also 
  hairy 
  ; 
  balancers 
  small, 
  clubbed, 
  and 
  white 
  ; 
  

   six 
  legs 
  woolly 
  ; 
  the 
  feet 
  fine-pointed, 
  the 
  tips 
  black 
  ; 
  length, 
  f 
  line 
  ; 
  expanse, 
  3 
  lines. 
  

  

  "In 
  February, 
  1846, 
  the 
  larvse 
  and 
  pupae 
  were 
  abundant 
  in 
  the 
  rotten 
  

   potatoes, 
  also 
  in 
  decaying 
  leaves 
  and 
  dung-hills, 
  and 
  the 
  flies 
  have 
  been 
  

   bred 
  by 
  Mr. 
  Haliday 
  from 
  putrescent 
  fungi. 
  These 
  flies 
  sometimes 
  

   swarm 
  in 
  out-houses 
  and 
  about 
  drains 
  in 
  spriug 
  and 
  autumn. 
  

  

  "The 
  larvEe 
  are 
  not 
  i 
  line 
  long, 
  yellowish-wbite, 
  cylindrical, 
  spindle- 
  

   shaped, 
  with 
  eleven 
  distinct 
  annulations 
  besides 
  the 
  head, 
  which 
  is 
  

   triangular 
  ; 
  the 
  tail 
  is 
  elongated 
  and 
  tubular. 
  The 
  pupa 
  is 
  about 
  f 
  line 
  

   long, 
  ocherous, 
  and 
  ferruginous; 
  it 
  is 
  elongate-ovate 
  m 
  repose, 
  but 
  the 
  

   body 
  can 
  be 
  stretched 
  out 
  and 
  attenuated 
  when 
  disturbed; 
  from 
  the 
  fore- 
  

   head 
  project 
  two 
  slender 
  appendages, 
  like 
  horns 
  ; 
  on 
  either 
  side 
  are 
  laid 
  

   the 
  short, 
  stout 
  antennce, 
  and 
  the 
  wings 
  meet 
  over 
  the 
  breast, 
  with 
  the 
  

   legs 
  stretched 
  out 
  between 
  them 
  ; 
  the 
  abdominal 
  segments 
  are 
  ciliated 
  

  

  and 
  the 
  tail 
  is 
  forked. 
  , 
  ^ 
  ^ 
  ^.i 
  

  

  "Several 
  species 
  of 
  a 
  little 
  swarthy 
  two- 
  winged 
  fly 
  were 
  bred 
  from 
  ttie 
  

   decaying 
  potatoes 
  in 
  multitudes. 
  They 
  are 
  called 
  Sctara 
  by 
  Meigen 
  

   and 
  Molohrus 
  by 
  Latreille. 
  The 
  larvae 
  I 
  received 
  from 
  Mr. 
  Graham 
  ; 
  

   they 
  are 
  slender 
  worms, 
  about 
  | 
  inch 
  long, 
  whitish, 
  and 
  opaque, 
  but 
  

   when 
  immersed 
  in 
  water 
  they 
  become 
  perfectly 
  transparent, 
  exhibiting 
  

   the 
  ocherous 
  viscera 
  and 
  the 
  food 
  digesting 
  in 
  the 
  stomach 
  ; 
  when 
  m 
  

   motion 
  they 
  taper 
  toward 
  the 
  head, 
  which 
  is 
  oval, 
  horny, 
  black, 
  and 
  

   shining; 
  the 
  body 
  is 
  composed 
  of 
  thirteen 
  segments, 
  with 
  seven 
  or 
  

   eight 
  spiracles 
  on 
  each 
  side 
  ; 
  the 
  tail 
  is 
  broad 
  and 
  rounded, 
  but 
  slightly 
  

   pointed 
  in 
  the 
  center. 
  The 
  pupa 
  is 
  shorter, 
  cylindrical, 
  elhptical, 
  and 
  ot 
  

  

  