Note. — The articles of this report have all been previously 
printed in the Bulletin of the Agricultural Experiment Station with 
the exception of that on the elm tvvig-girdler, on pages 118-134, 
which is now published for the first time. Plates IX., X., and XI. 
of this report are also here first printed, the others having been 
already once used in the experiment station articles, except Plate 
VIII. and the frontispiece, which were printed in illustration of 
Article I of Volume VII. of the Bulletin of the Illinois State Lab- 
oratory of Natural History. 
