INDIRECT BENEFITS DERIVED FROM INSECTS. 285 



singular procedure with that species, may be to allure 

 the birds, which it preys upon, to a particular spot 3 . 



Amongst the Pices or Pies the Crotophaga, called the 

 Ani, which is a native of Africa and America, lives upon 

 the locust and Acarus ricinus^ which it picks in great num- 

 bers from the backs of cattle ; but none are greater de- 

 vourers of insects in this order than rooks. It is for the 

 grubs of Melolontha, Tipula, &c, that they follow the 

 plough ; and they always frequent the meadows in which 

 these larvee abound, destroying them in vast numbers. 

 Kalm tells us, that when the little crow was extirpated 

 from Virginia at an enormous expense, the inhabitants 

 would willingly have brought them back again at double 

 the price b . The icteric oriole is kept by the Americans 

 in their houses for the sake of clearing them of insects ; 

 and the purple grackle is so useful in this respect, that 

 when, on account of their consuming grain, the Ameri- 

 can farmers in New England offered a reward of three- 

 pence a head for them, and they were in consequence 



a According to Mr. Heckewelder(TVrt«s. Am. Phil. Soc. iv. 124.) 

 L. Excvbitor, called in America the nine-killer, from an idea that it 

 transfixes nine individuals daily, treats in this manner Grasshoppers 

 only ; while L. Cotturio would seem to restrict itself chiefly to Scara- 

 bcei, two of which Mr. Sheppard once observed transfixed in a hedge 

 that he knew to be the residence of this bird. Kugellan even thinks 

 that it impales only S. vernalis, which he has often found transfixed, 

 but never S. stercorarius. (Schneid. Mag. 259.) I must remark, 

 however, that I last summer observed two humble-bees quite alive, 

 impaled on the thorns of a hedge near my house, which had most pro- 

 bably been so placed by this species, L. Excubitor being rarely found 

 except in mountainous wilds. (Bewick's Birds, i. 61.) And Prof. 

 Sander states that on opening this bird (L. Cotturio) he has sometimes 

 found in its stomach nothing but grasshoppers, and at others small 

 beetles and other insects. Naturforscher Stk. xviii. 234. 



b Stillingfl. Tracts, 175. Linn. Travs. v. 105. note b. 



