[105] Report of the State Entomologist. 247 



The grain aphis owes its conceded claim to a place among the more 

 injurious insect pests of the agriculturist, in consideration of the veg- 

 etation it attacks, its capability for harm, and its wide distribution. 

 It is very generally distributed throughout the grain-producing 

 regions of both continents. It infests all of the more valuable 

 grain crops, as wheat, rye, barley, oats, and many of the other mem- 

 bers of the grass family (Graminece). It is of common occurrence, 

 being found in our fields nearly every year, but, like many other of 

 the more destructive insects, it is only in certain years that, in 

 particular localities, unknown conditions concur in causing its 

 excessive multiplication, when its injuries are very great, even to the 

 almost complete or the entire destruction of the crops attacked. 

 Such an instance occurred in many of the Middle and Eastern States 

 in the year 1861, when, as a new pest of the grain crops, it came under 

 the observation of Dr. Fitch, who gave it careful study and con- 

 tributed an excellent paper upon it, in his Sixth Report on the Insects 

 of New York, first published in the Transactions of the New York 

 State Agricultural Society for that year. In it are contained its 

 European history, account of its first appearance in this country, 

 description of its three forms, its propagation and habits, its parasitic 

 and other enemies, etc. As this paper is accessible to most who may 

 desire the information that it embodies, only a brief notice will be 

 presented of the insect in this report. 



Different forms of the Aphis. 

 Dr. Fitch observed four different forms of the insect through the 

 season, viz.: 1st, the young louse or larva; 2d, the pupa; 3d, a wing- 

 less female; and 4th, the winged female. The last two of these are 

 shown in the accompanying figures. 



Fig. 30 — Wingless and winged females of the grain aphis, Siphonophoka aven^:. 



(After Fitch.) 



The wingless female is described as varying remarkably in color, 

 being either red, green, brown, or yellow. The front is convex in the 



