4t4 Food of Rooks. [oct., 



the first containing grain, &c., eaten by the rooks, and the 

 second the harmful insects they devoured : — 



I. Grain &c. taken by 4,03c Rooks. 



Sprouied : — 





Wheat 15,578 grains. 



Barley 10,465 



Oats I: 



2,787 „ 



Maize 



987 „ 



Buckwheat... 



1,777 „ 



Potatoes 



587 



Unsprouted : — 





Barley 



247 grains. 



Maize 





Rye 



358 » 



II. Harmful Insects taken by 4,030 Rooks. 



Ale'olontha vulgaris (cockchafer) beetles 



2,222 



white grubs 



:.. 2,264 



E later ox " click " beetles 



2,307 



larvae (wireworms) 



... 1,589 



Weevils (total) 



... 14,710 



Caterpillars (total) 



9,126 



7z/z^/a larvae (leather jackets) ... 



... 3,411 



Ci2J-JzV(5r (tortoise beetle)... 



2,062 



Chrysomelidit, sp. (leaf beetles), total ... 



... 2,113 



Phyllopertha, Anisoplia, Hoplia 



... 1,717 



Silpha, sp. (burying or carrion beetles)... 



984 



Bibio, grubs (hair gnats) ... 



406 



Zabnis gibhus (corn ground beetle) 



86 



It may be remarked that the totals of these two tables show 

 that against the 42,826 grains of corn and potatoes taken we 

 have to place to the credit of the rooks the destruction of no 

 less than 43,997 insects harmful to agriculture. Considering the 

 cockchafers alone, Dr. Hollrung suggests that if the 2,222 

 beeiles were equally divided as regards sex, and the females laid 

 their ordinary quota of 60-70 eggs, a total of 66,660 eggs 

 would be laid. In a normal season perhaps one-half would 

 hatch, thus giving rise to 33,330 white grubs. It is considered 

 that ten cereal plants form a low estimate of the plants destroyed 

 by each grub per annum. This would mean that the progeny 

 of the 2,222 beetles devoured by the rooks would have destroyed 

 333)300 cereal plants per annum. But the grubs live about 

 three years in the soil, during the last two of which they are 

 very destructive to living roots, &c. Supposing in the second 

 year 50 per cent, of the larvae are killed or die from various 

 causes, there will still be 16,665 larvae v/hich will destroy a 



