Chapter 13. 



INJURIOUS ANIMALS OTHER THAN INSECTS. 



Injurious and beneficial Animals. Birds and the need for 

 scientific investigation with reference to their food at different 

 seasons of the year. Eelworms and more especially the Stem 

 Eel-worm and the Knot Root Eelworm. Pulmonate Molluscs 

 (Snails and Slugs}. The Black Currant Gall Mite. 



All who engage in agricultural or horticultural pur- 

 suits sooner or later have to concern themselves with some 

 of the forms of animal life which are associated with their 

 plants. Very frequently certain of these animals are 

 directly injurious to the operations of man, but there are 

 others which, on the contrary, are distinctly beneficial in 

 their effects. It is, therefore, a matter of considerable 

 importance to be able to discriminate between these two 

 classes, for it is obviously bad policy to devote time and 

 money in destroying organisms w r hich are beneficial in 

 their action. The animal kingdom comprises a vast 

 assemblage of different forms, but fortunately for our 

 present purpose we need only concern ourselves with a 

 relatively small proportion of their number. These in- 

 clude certain birds, species of Nematodes or Eelworms, 



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