﻿EFFECT 
  OF 
  TEMPERATURE 
  OX 
  ACTIVITY 
  OF 
  LARVAE. 
  25 
  

  

  made 
  to 
  Mr. 
  D. 
  M. 
  Rogers. 
  The 
  hatching 
  thus 
  recorded 
  took 
  place 
  

   in 
  localities 
  which 
  became 
  warm 
  very 
  early 
  in 
  the 
  spring, 
  but 
  this 
  

   serves 
  as 
  a 
  basis 
  for 
  comparing 
  the 
  temperatures. 
  

  

  The 
  entire 
  period 
  of 
  hatching 
  usually 
  extends 
  over 
  a 
  month. 
  In 
  

   fact, 
  in 
  some 
  parts 
  of 
  the 
  infested 
  territory 
  where 
  the 
  summer 
  season 
  

   is 
  short, 
  owing 
  to 
  the 
  high 
  altitude 
  or 
  to 
  the 
  northern 
  latitude, 
  the 
  

   period 
  is 
  considerably 
  longer. 
  

  

  Mr. 
  Henry 
  L. 
  Mclntyre, 
  one 
  of 
  the 
  general 
  foremen 
  in 
  charge 
  of 
  

   moth 
  work 
  for 
  the 
  Bureau 
  of 
  Entomology, 
  informs 
  me 
  that 
  several 
  

   unhatched 
  gipsy-moth 
  egg 
  clusters 
  were 
  found! 
  July 
  1, 
  1910, 
  at 
  

   AVinchendon, 
  Mass., 
  by 
  scouts 
  who 
  were 
  working 
  under 
  his 
  direction. 
  

   The 
  clusters 
  were 
  well 
  formed 
  and 
  were 
  apparently 
  fertile, 
  although 
  

   this 
  point 
  was 
  not 
  fully 
  determined. 
  

  

  He 
  also 
  reports 
  that 
  in 
  the 
  spring 
  of 
  1908 
  he 
  found 
  egg 
  masses 
  

   in 
  maple 
  swamps 
  near 
  Portsmouth, 
  N. 
  H., 
  that 
  had 
  not 
  hatched 
  on 
  

   June 
  15. 
  In 
  1909 
  he 
  observed 
  several 
  egg 
  clusters 
  that 
  had 
  just- 
  

   hatched, 
  in 
  a 
  stone 
  wall 
  at 
  Gilford, 
  N. 
  H., 
  on 
  June 
  4. 
  

  

  This 
  shows 
  the 
  variation 
  in 
  time 
  of 
  hatching 
  in 
  different 
  localities 
  

   and 
  situations, 
  but 
  it 
  is 
  exceptional 
  for 
  hatching 
  to 
  take 
  place 
  after 
  

   June 
  1. 
  Additional 
  data 
  on 
  the 
  dates 
  of 
  hatching 
  have 
  been 
  fur- 
  

   nished 
  by 
  Mr. 
  F. 
  A. 
  Bates, 
  who 
  has 
  for 
  many 
  years 
  been 
  prominently 
  

   connected 
  with 
  moth 
  work, 
  and 
  from 
  various 
  other 
  careful 
  observers. 
  

  

  The 
  accompanying 
  diagram 
  (fig. 
  1) 
  shows 
  the 
  range 
  in 
  tempera- 
  

   tures 
  for 
  20 
  days 
  preceding 
  and 
  10 
  days 
  following 
  the 
  first 
  report 
  of 
  

   hatching 
  for 
  the 
  years 
  1908 
  to 
  1911. 
  It 
  will 
  be 
  noted 
  that 
  in 
  1910, 
  

   when 
  hatching 
  was 
  recorded 
  April 
  3, 
  nearly 
  two 
  weeks 
  of 
  warm 
  

   weather 
  immediately 
  preceded 
  hatching. 
  In 
  1909 
  the 
  warm 
  weather 
  

   was 
  interrupted 
  by 
  several 
  cold 
  days, 
  while 
  in 
  1908 
  and 
  1911 
  hatching 
  

   took 
  place 
  during 
  the 
  only 
  warm 
  period 
  that 
  occurred 
  in 
  the 
  month. 
  

   This 
  last 
  record 
  shows 
  the 
  tendency 
  of 
  the 
  eggs 
  to 
  hatch 
  at 
  the 
  first 
  

   opportunity 
  as 
  the 
  season 
  grows 
  late. 
  

  

  EFFECT 
  OF 
  TEMPERATURE 
  ON 
  ACTIVITY 
  OF 
  LARV^. 
  

  

  As 
  the 
  activity 
  of 
  the 
  caterpillars 
  after 
  hatching 
  as 
  well 
  as 
  their 
  

   emergence 
  from 
  the 
  eggs 
  depends 
  upon 
  the 
  temperature, 
  several 
  ex- 
  

   periments 
  were 
  made 
  to 
  determine 
  the 
  temperature 
  at 
  which 
  the 
  

   larva' 
  are 
  most 
  active, 
  since 
  it 
  is 
  obvious 
  that 
  little 
  distribution 
  by 
  

   wind 
  would 
  be 
  possible 
  unless 
  the 
  larva 
  4 
  were 
  active 
  during 
  the 
  first 
  

   stage. 
  Accordingly, 
  a 
  series 
  of 
  laboratory 
  tests 
  were 
  made 
  by 
  Mr. 
  

   Collins. 
  For 
  this 
  purpose 
  a 
  constant-temperature 
  incubator 
  was 
  

   used, 
  it 
  being 
  arranged 
  in 
  such 
  a 
  way 
  that 
  the 
  thermostat 
  which 
  

   regulated 
  the 
  heat 
  supplied 
  by 
  electric 
  incandescent 
  lamps 
  could 
  be 
  

   changed 
  without 
  opening 
  the 
  incubator. 
  

  

  