THE ANIMAL KINGDOM. 99 



and open out extensive clearings in their sombre shades 

 more quickly than the axe of the woodman. 



In some regions of Europe a little yellow fly streaked with 

 black, the Chlorops lineata, alarms the farmer by attack- 

 ing the grain crops. Linnaeus says that in Sweden this fly, 

 unassisted, destroys more than the fifth part of the barley 

 crops, equivalent at least to 100,000 tons. In Central 

 France this insect sometimes devours half the ears of corn 

 in the fields. 1 Another, the olive-tree Dacus, is the cause 

 of losing every year 3,000,000 olives. Finally, a butterfly, 

 the Pyralis of the vine, carries despair into all our wine 

 countries, which have now for a long time vainly implored 

 the aid of science. 



When trees, attacked by dense swarms of insects, do not 

 sink under their fangs, they escape with singular deform- 

 ities. 2 



The sting of an extremely small insect, the woolly aphis 

 (Aphis lanigera), which, when on the branches, would 

 elude the eye were it not enveloped in a tuft of white wool, 

 covers our apple-trees with numerous excrescences, and 

 these often end by killing it. 



The wounds inflicted by insects also give rise to those 



1 The Chlorops lineata, a fly the name of which indicates its yellow colors 

 barred with black, makes such havoc in the wheat fields that those who have 

 followed up its history maintain that it would soon annihilate this cereal alto- 

 gether if its increase in numbers were not checked by different causes. Another 

 insect undertakes this task, and carries it out to a considerable extent; this is 

 Alysia Olivieri, which perforates the eggs of the Chlorops with its ovipositor, in 

 order to secure a shelter for its own offspring. 



2 In the magnificent plates of Ratzeburg's work on the insects of the forest 

 may be seen a representation of a forest quite deformed by the attacks of the 

 pine-twister. Hylophthires et lews Ennemis. Leipzig, 1842. 





