23 



identified. During the present season the following species have 

 been found noticeably injurious to this crop in Illinois : 



The Eed-Legged Gkasshoppers, Pezotettix femur-rubrum, DeG., and 

 P. atlanis, Riley. The most evident injury to corn done by these species 

 which came to my knowledge, was that reported by Dr. F. W. 

 Goding. In a letter dated August 29, he says : "For the first time 

 in my life I have this summer seen damage done to crops by 

 locusts. The corn bordering on grass lands has been considerably 

 injured, causing the ear to be small and undeveloped. They ate 

 the leaves, husks, tops and ends of the ears. The injury was done 

 by the fcinur-ruhrmn and atlanis; also many narrow winged 'katydids' 

 were with them." [Probably Orchelimum vulgarc] 



Acridiiim americanum, Drury. — In Union and Perry Counties, in 

 September this great bird grasshopper (so closely related to the 

 Egyptian locust as to startle one as he notices its abundance in ex- 

 treme Southern Illinois), was occasionally found doing considerable 

 damage in the borders of cornfields, sometimes completely stripping 

 the stalks of leaves. It never swarms, however, and has not the 

 dreaded power of migration of its relative, and has hitherto done no 

 serious injury. 



Caloptenus differentialis, Thos. — This species, one of our most 

 abundant, was the commonest grasshopper in cornfields in Southern 

 Illinois this fall, feeding not only on the leaves, but on the corn at 

 the tip of the ears, and sometimes gnawing down the side of the 

 cob. 



Orchelimum vulgarc, Harris. — In some situations this common grass 

 locust was about as abundant as Caloptenus differentialis, and sim- 

 ilarly injurious. 



8. A Contribution to the Life History of the Corn Plant Louse. 



{Aphis maidis. Fitch.) 



Order Hemiptera. Family Aphidid.e. 



By H. Garman. 



Our knowledge of this insect is made up of scattered contributions 

 which have been made from time to time since the year 1856, when 

 Dr. Asa Fitch, in his second report on the noxious, beneficial and 

 other insects of the State of New York, named the insect and de- 

 scribed the aerial form. At the time his report was written, Dr. 

 Fitch had seen only the larva, wingless female, pupa and winged 

 female of the aerial form, and these were supposed by him to occur 

 only upon the peduncles of corn ears. 



Mr. B. D. Walsh next discovered the root form and described its 

 larva, apterous female, pupa and alate female (Proc. Ent. Soc. Phil., 

 1863, and Trans, 111. State Ag. Soc, 1865). He mentions the fact 

 that this form is attended by small ants. 



In his list of the plant-lice of the United States, published in 

 Bulletin '2 of the Illinois State Laboratory of Natural History, 1877, 

 Dr. Cyrus Thomas adds to our information the statement that the 

 aerial form occurs on the corn silks as well as on the ear-stalks. 



