OBSERVATIONS ON A GALL APHID (APHIS ATRIPLICISL.).* 



Paul Hayhurst. 



The subject of this article is the common greenish insect of 

 the genus Aphis which colonizes the dorsal surface of the leaves 

 of the white goosefoot or lamb's quarters, Chenopodium alhtim, 

 and the nearly allied orache, Atriplex patula, in summer. The 

 margins of the infested portion of the leaf always curl up longi- 

 tudinally and meet above the midrib, forming an imperfectly 

 closed tube. 



According to the determinations of Mr. T. A. Williams and of 

 Doctor Forbes, Aphis atriplicis also attacks the leaves of culti- 

 vated beets in Nebraska and Illinois. This would not be at all 

 surprising, since the genus Beta is closely related to Chenopodium 

 and Atriplex. Doctor Bruner wrote me that Mr. Williams was 

 well acquainted with the insect and knew its characteristic habits 

 on goosefoot. This aphid is very abundant on the common 

 goosefoot and orache, from which it might easily become trouble- 

 some on beets. 



At Fredonia, N. Y., it was everywhere abundant on the white 

 goosefoot during August, 1908, when I first became familiar with 

 its habits, although I did not determine it specifically until the 

 following January. Most plants of this host were badly infested 

 both in the vicinity of Fredonia and also at Lily Dale, Jamestown, 

 and Chautauqua, N. Y. It has been reported as infesting this 

 plant from ]\Iissouri, Kansas, Minnesota, Colorado, Illinois and 

 Nebraska. Professor G. Del Guercio, Florence, Italy, writes me 

 that this species is everywhere common in Europe on plants of 

 the goosefoot family. I find in the literature that it has been 

 reported from the following countries : Sweden, Germany, Italy, 

 England and Belgium. 



In habits this species is unique. The insects were infesting 

 only the dorsal surface of the leaves and no other part of the 

 plant when I was studying them last August. They were clus- 

 tered chiefly along the midribs and main veins. The elongated 

 galls (Fig. i), which were formed by the sucking on the upper sur- 

 face, partially protected the occupants from rain and sun. The 

 margins of the leaves were never rolled in or convoluted more than 

 I have shown in Fig. i, a-b, which are cross sections of represen- 



* Contributions from the Entomological Department of Busscy Instittition, 

 Harvard University, No. 5. 



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