INJUUIOUS INSECTS. 55 



of all the insects on this grain the past summer; whilst in 

 France, the preceding summer, only 7 per cent, of the insects 

 on wheat were of this species. In France the parasitic des- 

 troyers amounted to 85 per cent. ; while in this country our par- 

 asites form only 10 per cent." 



A true knowledge of practical entomology may well be said to 

 be in its infancy in our own country, when, as is well known to 

 agriculturists, the cultivation of wheat has almost been given 

 up in New England, New York, Pennsylvania, Ohio and 

 Virginia, from the attacks of the wheat midge, Hessian fly, 

 joint worm, and chinch bug. According to Dr. Shimer's 

 estimate, says Mr. Riley, in his Second Annual Report on the 

 Injurious Insects of Missouri, which may be considered a reason- 

 able one, "in the year 1864 three-fourths of the wheat, and 

 one-half of the corn crop were destroyed by the chinch bug 

 throughout many extensive districts, comprising almost the 

 entire North- West, At the annual rate of increase, according 

 to the United States Census, in the State of Illinois, the wheat 

 crop ought to hare been about thirty millions of bushels, and 

 the corn crop about one hundred and thirty-eight million 

 bushels. Putting the cash value of wheat at $1.25, and that of 

 corn at 50 cents, the cash value of the corn and wheat 

 destroyed by this insignificant little bug, no bigger than a grain 

 of rice, in one single State and one single year, will therefore, 

 according to the above figures, foot up to the astounding total 

 of ovei' seventy-three millions of dollars ! " 



The imported cabbage butterfly (Pieris rapae), recently intro- 

 duced from Europe, is estimated by the Abb6 Provancher, a 

 Canadian entomologist, to destroy annually two hundred and 

 forty thousand dollars' worth of cabbages around Quebec. The 

 Hessian fly, according to Dr. Fitch, destroyed fifteen million 

 dollars' worth of wheat in New York State in one year (1854). 

 The army worm of the North (Leucania unipuncta), which was 

 so abundant in 1861, from New England to Kansas, was re- 

 ported to have done damage that year in Eastern Massachu- 

 setts exceeding half a million of dollars. The joint worm 

 (Isosoma hordei) alone sometimes cuts off whole fields of 

 grain in Virginia and northward. The Colorado potato beetle 

 is steadily moving eastward, now ravaging the fields in Indiana 

 and Ohio, and only the forethought and ingenuity in devising 

 means of checking its attacks, resulting from a thorough study 



