SB 
818 
C578 
ENT |0. 43, SECOND EDITION.! Issued February 25, 1909. 
ited States Department of Agriculture, 
BUREAU OF ENTOMOLOGY, 
L, O. HOWARD, Entomologist and Chief of Bureau. 
J 
THE PEA APHIS.’ 
| | 205164 
(Macrosiphum pisi Kalt.) 
By F. H. CHITTENDEN, 
In Charge of Truck Crop and Special Insect Investigations. 
One of the most destructive and troublesome insects of recent years 
is a green plant-louse which, from its injury to peas, is known as the 
= FOTO TTT —r 
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e 
Fia. 1.—Pea aphis (Macrosiphum pisi): a, Winged female; b, same from side, with wings folded in 
natural position, as when feeding; c, apterous female; d, nymph in last stage; e, third joint of 
antenna of winged form. a-d, Muchenlarged; e, more highly magnified. (Author’s illustration.) 
pea aphis. Since it first attracted attention by its ravages in May of 
1899 it has steadily increased in injuriousness, and has been the cause 
1 Reprint, with slight revision, of Circular No. 43, Second Series, entitled ‘‘ The 
Destructive Green Pea Louse (Nectarophora destructor Johns).’’ 
2 Several articles have been published on this insect, notably by Messrs. John- 
son and Sanderson, as well as by the writer. The former gave it the scientific 
name Nectarophora destructor, but the latter gives reasons to show that this 
insect is in reality the European pisi Kalt.; hence the present change of title. 
A6-—49 
