October, '10] DAVIS: ILLINOIS APHIDID.E 407 



Ore., August 20, 1909, on Cornus sp. The fall migrants were just 

 beginning to form colonies on the leaves. This is an abundant species 

 in Colorado, the eggs being deposited on twigs of Cornus sto- 

 lonifera in the fall by apterous females that are the young of the 

 migrants. In the spring the migrants leave the dog-wood and go to 

 Helianthus for the summer. We have mam- times observed this habit 

 in Colorado, and Mr. L. C. Bragg has artificially colonized this species 

 both ways between these plants. 



The figures are from fall migrants, taken at Fort Collins, Col., on 

 Cornus stolonifera, Sept. 29, 1909. We have also taken this louse on 

 Iva xanthifolia and in large numbers upon Ribes aurem. The male 

 antenna is peculiar in having several sensoria upon all the joints beyond 

 the second. 



A . gillettei Cowen is a synonym of this species, but helianthi Monell 

 seems probably to be a distinct species judging from an examination of 

 balsam material sent me by Mr. Monell, and taken at St. Louis, Mo., 

 July 7, 1910. Monell's specimens are somewhat smaller and have 

 relatively shorter antennae and cornicles, and the alate viviparse lack 

 the blackish patches at the base of each cornicle. The two forms, if 

 distinct, are very closely allied. I find no difference in number or dis- 

 tribution of the sensoria. 



Plate 26. Aphididce. Unless otherwise marked, all figures are multiplied 70 times, 

 and are from alate viviparous females. 1 and 2, Aphis salicicola; 3, 4, and 5, A. sorbi; 

 6 and 7, A. riparice (:?); 8 and 9, Aphis asclepiadis; 10 and 11, A. pomi; 12 and 13, A. 

 gossypii; 14 and \o, A. spiroeella; 16 and 17,^4. cardui; 18 and 19, A. ce phalanthi; 

 20 and 21, A. sambuci; 22 and 23, A. cerasifolii; 24 and 25, A. bakeri; 26 and 27, 

 (two views), A. brassicoe; 28 and 29, A. maidi-radicis; 30 and 31, yl. rumicis; 32, 33 

 and 34 (two \dews), .4. atriplicis; 35, 36, 37 (male), 38 (male), of A. cornifolice. — 

 Miriam A. Palmer, Delineator. 



A LIST OF THE APHIDID.E OF ILLINOIS, WITH NOTES 

 ON SOME OF THE SPECIES 



By John J. DA^^s, Office of the State Entomologist, Urbana, Illinois 



In this catalogue of the Aphididse of North America (1901), Professor 

 W. D. Hunter lists 98 species as having been recorded from Illi- 

 nois. Since then, from records in literature and personal collections, 

 the list has been increased to 170 species. Many more have been 

 collected by us which we are at present unable to identify, either 

 because of too little material or the apparent confusion of certain 

 groups, which will require larger numbers of collections to work out 

 satisfactorily. Following each species are one or more references 

 to the most comprehensive descriptions of the various forms in Amer- 



