PARASITIC ENEMIES OF TREES AND PLANTS 



By Dr. R. W. Shufeldt, C. M. Z. S., etc. 



(WITH PHOTOGRAPHS BY THE AUTHOR) 



OF all the various lines of study and research in nat- 

 ural history none is morie interesting than that 

 branch of general botany dealing with abnormal plant 

 growths that are the result of injuries caused by insects. 

 Many are more or lesse-familiar with them as they occur 



GALLS DESTROYING A FLOWER 



Fig. I This quite unique illustration shows a specime,n of 

 Black-eyed Susan (Rudbcckia hirta) in its last stages of de- 

 struction by masses of dark green galls, each as big as a horse 

 chestnut. 



on the twigs, leaves and other parts of trees and plants, 

 for they are conspicuous objects when seen in the forest 

 and elsewhere at various seasons of the year, from early 

 spring to late autumn. They have long been known to for- 

 esters and students of plant pathology as galls. Even as 

 far back as the days when Pliny wrote, that is, along in 

 50 to 60 A. D., that famous naturalist of antiquity had 

 paid some attention to them ; and when his Natural 



History came to be published his readers found it stated 

 therein that a gall on a tree was produced at night, and 

 by some kind of a fly, the larva of which subsequently 

 ate up the gall. Others of those times believed this, 

 while still others claimed that tree galls were the home 

 of certain worms or spiders. Prophesies of what the en- 

 suing year would have for people of the times and of 

 events that would come to pass, were based upon such 

 data that is, whether worms, spiders or flies were to be 

 the more numerous during that particular year. The 

 matter did not rest here, however, although for a long 

 time some very ridiculous notions about galls on trees 

 and plants were rife. For instance, a poet, who was 

 also a doctor of medicine one Redi of the 17th century, 

 held that all trees and plants were endowed with a soul 

 a vegetable soul and that that phytological phantom was 

 not only responsible for flowers and fruits and all their 



TICK TREFOIL SHOWING HYPERTROPHY 



Fig. 2 Hypertrophy in plants is not a common disease, and 

 the case here shown is one of extreme rarity. It is the only 

 specimen discovered by the, author after rambling through North 

 American woods and fields for more than half a century. 



