332 ILLINOIS STATE HORTICULTURAL SOCIETY. 



out the evil until all is lovely. What I have said of fruits may be applied 

 to all the branches of our profession. It appears to me that this investiga- 

 tion into vegetable life and beauty should be a paramount business with 

 us to that of geology and astronomy, for it is of more practical use; it 

 comes into our every-day business, and begs for a place at our firesides. 



Studies are said to be a discipline of the mind ; yet I believe there is 

 none more really good, benign and refining, than the study and care of 

 plants. No schools are so well adapted to teach this as our Agricultural 

 Colleges, yet it should be continued into our common schools. The weight- 

 ier matters of science should be taught, but the finer qualities of our 

 science should no longer be neglected, but progress until our girls can 

 be taught how and where the rose acquires its beauty and fragrance ; that 

 they may command the elements in this science, as the telegrapher com- 

 mands electricity. 



Mr. Wier read an essay, as follows : 



ENTOMOLOGY— STUDY OF A LEAF. 



September I, 1873. — Passing by a Cottonwood (/*. Manlifera)lo- 

 day, I observed that its foliage was yellow and falling. Having leisure, 

 I stopped to inquire into the cause of its losing its leaves so early in 

 the season. Plucking a leaf, a glance at its under surface showed it 

 to be covered in patches by a rust-colored fungus, which was in itself 

 a sufficient cause for the destruction of the leaves. But noticing a 

 brighter red speck on the leaf, I brought my pocket magnifier to bear 

 on it, and found it to be a larva or maggot of perhaps a small gnat, 

 feeding upon the fungus. At the same time, I noticed that these specks 

 of fungi radiated from a central point, apparently the puncture of a 

 leaf louse. On a close inspection of the under surface of the leaf, a clus- 

 ter of Aphides, or leaf lice, were found, with their beaks inserted into 

 the cellular portion of the leaf; and although these lice were not 

 small for leaf lice, their color was so peculiar — so near the color of the 

 leaf — that they would not be readily noticed. A careful search among 

 these lice brought to light a maggot, or larva, preying upon them. It, 

 also, was so nearly the color of the under surface of the leaf, and although 

 of considerable size, that it would not have been seen even with the mag- 

 nifier, had it not, while in focus, captured a louse and reared up, as such 

 larvae do, while sucking its juices. This was apparently the larvae of a 

 large gray gnat. Here, then, was a sufficient reason for the early defolia- 

 tion of the young, thrifty Cottonwood tree, from which the leaf had 

 been plucked ; and I thought, of course, that this study was ended. 



But as I was casting the leaf aside, the sunlight glimmered from a 

 fine, silken web, near the base of it. Bringing this web into the focus of 

 my glass of highest power, a busy colony of mites (acari) were disclosed. 

 (Acart, or mites, are for the most part very small animals, many of them 

 not discernible with the naked eye ; the ones on this leaf, for instance, 

 showing a mere speck on white paper, and even there would hardly be 

 noticed, except when in motion ; they are not true insects, having no 



