310 Friends and Foes 



it is probably from this that the next year's crop 

 springs, though some have declared that the ants 

 actually sow as well as reap. Harvest over, the dry 

 stubble is cut and cleared away, and weeds are left to 

 grow as they will during winter, the work of cutting 

 them down beginning vigorously again in spring. 



These ants live chiefly on grass seeds, which they 

 gather from a distance as well as from the home crop ; 

 but though they do not steal food from the farmer, 

 they inflict much injury on his fields, and destroy many 

 an acre of produce, no amount of ploughing being suf- 

 ficient to drive them away. 



It is impossible even to enumerate the many animals 

 which feed upon plants, and, when allowed to increase 

 unduly, become the enemies instead of the friends of 

 vegetation, not merely checking overcrowding, but 

 destroying wholesale. 



We cannot attempt any description of the devasta- 

 tions caused by locusts, one of whom is reported by 

 Mahomet to have remarked, * We are the army of the 

 great God ; we produce ninety-nine eggs. If the 

 hundred were complete, we should consume the whole 

 earth and all that is in it.' Nor can we tell of the 

 ravages of the American crickets, which eat up a whole 

 crop of maize in a night ; or of the caterpillars, which 

 would completely destroy the tobacco plantations if 

 not constantly picked off leaf by leaf; or of the minute 

 beetles, whose grubs, penetrating between wood and 

 bark, destroyed in 1780 and the following years a 

 million fir-trees in the Harz mountains and Switzer- 

 land, 50,000 trees, chiefly oaks, more recently in the 

 Bois de Vincennes, and are causing avenues of fine 

 elms to disappear in the north of France. Green fly, 



