L107] 



Report of the State Entomologist. 



249 



This seasonal change of color, dependent upon the portion and con- 

 dition of the plant that nourishes them, together with the particular 

 food-plant on which they are observed, will fully explain the discrep- 

 ancies in the colors assigned to them by different writers. 



Abundance in the Year 1861. 

 Although a few individuals of this aphis had been observed sparsely 

 distributed in grain fields in the State of New York and elsewhere, it 

 had not been regarded as of any economic importance previous to the 

 year 1861. Dr. Fitch knew of no recorded instance in which an aphis, 

 although noted for rapid increase, had become thus suddenly and 

 excessively multiplied over such a wide extent of territory. In the 

 summer of 1861, throughout the greater portion of the New England 

 States, the State of New York, except its western section, the north- 

 eastern part of Pennsylvania, and in several localities in Canada, every 

 grain field was invaded by it, and in most of them it abounded in 

 incredible numbers. The yield of wheat was often reduced one-half, 

 while the oat crop suffered still more severely, to the extent of hardly 

 paying for the harvesting. 



Not Usually very Injurious. 

 No demonstration of the insect has since occurred at all comparable 

 with that above recorded. It continues, however, to make its appear- 

 ance almost annually in considerable or in insignificant numbers. 

 Examples of it are frequently sent to me with inquiries similar to the 

 following, which came from Albemarle county in Virginia : 



I send by this mail specimens of flies and aphides with which the 

 wheat-heads all through this section are affected. You will confer a 

 favor upon a large number of farmers in this county by giving the 

 name and nature of these insects, and the information whether they 

 will materially injure the crop. 



To the above, after giving the name, habits, etc., of the insect, it 

 was further stated : 



" The injuries will be in proportion to their number and of the 

 associated parasites. Heavy and long continued rains would be very 

 serviceable in checking the attack. It is not probable that it will 

 inflict severe injury to the wheat crop now attacked, for the kernels 

 will soon have so far advanced and hardened as no longer to serve 

 for food. Its numbers are, doubtless, being materially lessened by the 

 parasites and other predaceous insects which are preying upon it, 

 judging from the many dead aphids found in the package received. 

 The specimen separately inclosed and marked ' for examination and 

 name,' is the larva of a lady-bug, probably that of Hippodamia con- 

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