CHAPTER VI. 

 The Agents concerned in the Production of Galls. 



Five different orders of insects and two classes of worm-like 

 creatures are the principal producers of galls. Several species 

 of fungi added to these complete the list of all the agents at 

 present known as operating upon British plants for this purpose. 

 They are as follows : — 



I. Acarina, or Mites. 

 II. Anguillula, or Eclworms. 



III. Colcoptcra, or Beetles. 



IV. Diptera, or Flies (with two wings). 

 ^ V. Fungi, or Fungus. 



VI. Hemiptera-Homoptera, or Aphides. 

 VII. Heterocera, or Moths. 

 VIII. Hymenoptera, or Wasps (small). 



It has been found more convenient to place them in alpha- 

 betical order, rather than according to the natural order which 

 they severally occupy in the animal kingdom, or in relation 

 to the numerical preponderance of the species embraced in 

 each class. 



I. The Acarina, or Mites. 



These creatures are chiefly remarkable for their exceedingly 

 diminutive size. 



Andrew Murray, F.L.S., appears to have been the first in 

 this country to collate the information concerning the mites in 

 general. He isolated those which cause deformities on plants, 

 and placed above them the name of Gall-mites, classing them as 

 the sub-family Phytoptid^ ; and in his "Economic Entomology" 

 he gives a most excellent account of their habits, etc. 

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