78 OUTLINES OF FORESTRY. 



before the end of the second year, have produced eight hun- 

 dred and ten thousand females, and by the end of the third 

 year seven hundred and twenty-nine millions of the producing 

 sex, and the forest will have fed one billion five hundred and 

 six million six hundred thousand of the progeny of this one 

 parent." 



Concerning the destructive effects of the animal 

 kingdom, Geikie, in his " Text-Book of Geology,"* 

 page 456, writes : 



"Many animals exercise a ruinously destructive influence 

 on vegetation. Of the various insect plagues of this kind it 

 will be enough to enumerate the locust, phylloxera, and Colo- 

 rado beetle. The pasture in some parts of the south of Scot- 

 land has, in recent years, been damaged by mice, which have 

 increased in numbers owing to the indiscriminate shooting 

 and trapping of owls, hawks, and other predaceous creatures. 

 Grasshoppers cause the destruction of vegetation in some parts 

 of Wyoming and other Western Territories of the United 

 States. The way in which animals destroy each other, often 

 on a great scale, may likewise be included among the geologi- 

 cal operations now under description." 



Speaking of the influence of certain insects in 

 destroying forests from over extended districts, 



* Keprinted, by permission, from a " Text-Book of Geology," 

 by Archibald Geikie, LL.D. London : Macmillan & Co., 1882. 

 Pp. 971. 



