﻿PERIODICITY 
  OF 
  THE 
  HESSIAN 
  FLY. 
  

  

  Fly 
  years, 
  so 
  far 
  as 
  recorded. 
  

  

  233 
  

  

  -9 
  

  

  i 
  

  

  d 
  

   ^ 
  

   ^ 
  

  

  1 
  

  

  C8 
  

  

  ! 
  

  

  g 
  

  

  

  pi 
  

  

  1 
  

   < 
  

  

  i 
  

  

  d 
  

  

  1 
  

  

  i 
  

  

  'A 
  

   <s 
  

   H 
  

  

  en 
  

  

  1 
  

  

  P 
  

  

  7i 
  

  

  6 
  

  

  =8 
  

  

  i 
  

   

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1779 
  

  

  

  

  . 
  . 
  . 
  • 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  * 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  " 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  * 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ■ 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  " 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  • 
  •• 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  • 
  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  * 
  * 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1805 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1816 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ■ 
  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1829 
  

  

  1823 
  

  

  " 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ' 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  " 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1835 
  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1844 
  

  

  1844 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1845 
  

   1846 
  

  

  

  

  

  

  

  

  

  

  

  

  

  1S46 
  

  

  1846 
  

  

  

  

  

  

  

  

  

  

  

  

  

  1846 
  

  

  1847 
  

  

  

  

  

  

  

  

  

  

  

  

  1847 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1850 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1852 
  

  

  1852 
  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1854 
  

   1860 
  

  

  

  

  

  ■*■ 
  

  

  

  

  

  

  

  

  

  1854 
  

  

  

  

  1860 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  .... 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  ' 
  

  

  

  

  

  

  

  

  

  

  

  1867 
  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  

  ]8G8 
  

   ISCS) 
  

   ]870 
  

   lS7i 
  

   1872 
  

  

  

  

  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  "i870" 
  

   1871 
  

  

  "1873' 
  

  

  '1879' 
  

   1880 
  

  

  18fJ9 
  

  

  '1870 
  

  

  1871 
  

  

  1872 
  

  

  1873 
  

  

  1874 
  

  

  ]875 
  

  

  3876 
  

  

  J877 
  

  

  1878 
  

  

  

  

  18G9 
  

  

  

  

  

  

  

  :::::::::;: 
  ::i 
  

  

  

  

  

  

  

  

  

  

  ... 
  

  

  

  

  1871 
  

  

  1871 
  

  

  1872 
  

  

  1871 
  

   1872 
  

  

  

  

  

  

  

  

  

  

  1872 
  

  

  

  

  

  

  ... 
  

  

  

  

  

  

  

  

  

  

  1873 
  

  

  

  

  

  

  1874 
  

   1875 
  

  

  l^76 
  

  

  1^77 
  

   1878 
  

   1879 
  

   ]880 
  

   1881 
  

   1882 
  

  

  1874 
  

  

  

  1874 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  iS76 
  

  

  1876 
  

  

  1876 
  

  

  1876 
  

  

  1876 
  

  

  1876 
  

  

  1876 
  

  

  1876 
  

  

  1876 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1879 
  

  

  

  

  

  1879 
  

  

  

  

  ....... 
  

  

  

  

  .... 
  

  

  1880 
  

  

  

  

  1880 
  

   1881 
  

  

  ' 
  

  

  

  1880 
  

  

  

  

  

  

  

  1881 
  

  

  1881 
  

  

  1881 
  

   1882 
  

  

  

  

  1881 
  

  

  

  

  

  

  1882 
  

  

  

  

  

  

  

  

  1882 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  Allegliany 
  Moimtains. 
  

  

  