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CHAPTER IV. 



H YMENOPTEEA AK GALLS. 



Considered entomologically, the subject of gall-forming insects is a 

 very wide one, inasmuch as we find that certain insects belonging to 

 the various orders, from Acarina to Hymenoptera, form galls. The 

 galls on oak-trees are of special interest to the student of forest 

 entomology, and also to the biologist. 



Although the systematic study of galls is a comparatively modern 

 one, many kinds of galls were known to the ancients, and several 

 strange theories were from time to time propounded as to their origin 

 and growth. As it was known that vegetable galls were tenanted by 

 animal life, it was thought the plant contained a soul, able to impart 

 life to the animal. Some considered that galls were stepping-stones 

 from vegetable to animal life, while others thought eggs were drawn 

 up by the sap and ultimately developed into galls. Pliny, the Eoman 

 naturalist, knew that flies were produced from certain vegetable galls, 

 but he associated many superstitions with his knowledge. For in- 

 stance, he says that the events of the year were prognosticated as to 

 the respective larvae transforming into spiders, worms, or flies. 



The first systematic writer on galls was an Italian physician, who 

 gave an account of the galls of Italy and Sicily in 1686. The second 

 writer recorded, on the subject, was Dr Derham, Canon of Windsor, 

 who published his observations in the Boyle Lectures, 1711-1712. 

 It is questionable whether he knew of the Italian writings, but it is 

 said that when the two lists are compared the coincidence is very 

 striking. Neither of these writings was known to Linnaeus or 

 Fabricius. Linnaeus called the group Cynips, but comprised all 

 species of Hymenopterous parasites with true gall-makers. West- 

 wood, in 1839, working out the genus Cynips of Linnaeus, termed 

 the order Cynipidae, and gave some descriptive details. These, briefly 



