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PREVENTIVES. 
This insect is another one of the grain pests the ravages of which 
are not subject to immediate remedy in the field. The only steps of 
importance are in the line of prevention of future injury. A practical 
preventive suggested by the hibernating habit of the insect is in the 
deep plowing of the old wheat fields to bury the larve so deeply in 
the ground that they can not escape the following year. Asa further 
preventive, the chaff and screenings from the thrashings of wheat 
from an infested field should be promptly burned. The practice of 
rotation of crops is also applicable to this species and will be of value 
in proportion to the isolation of the tields or to the generality of its 
adoption. 
THE WHEAT PLANT-LOUSE. 
( Nectarophora cerealis Kalt. ) 
This plant-louse (fig. 11) is not one of the principal insect enemies 
of the wheat crop, but in some years, fortunately widely separated, it 
multiplies in enormous numbers and over wide regions, and becomes 
almost as destructive and occasions almost as much loss as does the 
Hessian fly or the chinch bug. Such periods of extensive damage 
were witnessed in 1861, and again in 1899. Local damage is of more 
frequent occurrence, and the species, in fact, occurs every year more 
or less, and often arouses fears which, for reasons to be subsequently 
explained, are not realized. 
Origin.— This insect is believed to be of European origin, and is the 
Siphonophora avene of Riley and other authors, a common wheat pest 
of the Old World. ‘There are, however, at least two other forms of 
plant-lice of similar habits in this country, and one of these is believed 
to be a native American species closely allied to the European one 
under consideration. The question of its origin, however, does not 
have much practical bearing on its present economic status in America, 
since it now occurs on this continent practically wherever wheat is ~ 
grown. One of the other plant-lice occurring on wheat, Vectarophora 
granaria Kby., known as the grain plant-louse, is sometimes nearly or 
quite as bad a pest as the species under discussion. In fact, almost 
any plant-louse that normally attacks the various wild or cultivated 
grasses or even other plants may occasionally occur in wheat. The 
habits of these other species which may sporadically appear on wheat 
are substantially identical with the one under discussion, and they need 
not be separately considered. Even the apple-tree plant-louse, Aphis 
mali, is occasionally found in wheat fields, and this has led to an erro- 
neous belief in some quarters that this insect and the wheat-louse are 
the same species and that the winter eggs of the former, which often 
thickly cover apple twigs, develop the spring generation of lice which 
appears on wheat in April. The absurdity of this point of view is 
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