576 



REPORT OF THE COMMISSIONER OF AGRICULTURK 



THE GRAIN APHIS. 



(SiphonopJiora avencc Fab.) 

 This species was observed infesting the heads of barley in considerable numbers, 

 and, when the grain was fully ripe and the winged adults ready to forsake the bar- 

 ley heads, we placed some of them in cages in which growing timothy, blue-gi-ass, 

 and red-top had been transplanted, with the hopes of learning Avhere the species 

 passed the svxmmer or until the young wheat appeared in the fall. The grasses were 

 kept alive, but the insects died, and no trace of a following generation was observed. 



INSECTS FREQUENTING OR DEPREDATING UPON BUCK- 

 WHEAT. 



So many reports of the aversion of insects for this plant are going the rounds of 

 the press, nearly all of which are unaccompanied by generally accepted authority, 

 that some exact data relative to the matter seems very desirable. It was with a 

 view of obtaining this information that, under Dr. Riley's instructions, we began a 

 series of observations, selecting as a basis one of the experiment plots of the Uni- 

 versity farm, which for the past five years has grown nothing but buckwheat, there- 

 by eliminating at the start any insects that miglit have been atti-acted by a previous 

 crop of grain or grass and remained over in either the adult or adolescent stages. 



As the object of the observations was a twofold one, i. e., to learn both the repul- 

 sive and the du-ect and indirect attractive properties of the growing plant, what may 

 at first appear to be over exactness will at once be seen to be quite essential, as the 

 occurrence of an insect but once or twice during several weeks is strongly indicative 

 of a repugnance for the locality. 



Observations began as soon as the plants were well above the surface of the ground, 

 and, until they were high enough to sweep with an insect-net, consisted of careful 

 inspection only, but later the entire plot was swept over at intervals of a few days 

 and a record kept of all captures. As some species visit the plants ait one time of 

 day and others at another, the time of sweeping was varied, in order to preclude the 

 possibility of any escaping notice in that way. These observations were carried on 

 until frost destroyed the plants. 



In the table the symbol ' 'A" signifies abundant; ' ' C," common. Where only very 

 few examples occvirred their number is indicated numerically. Unless otherwise 

 stated the adult stage is intended, and where a * follows the name of insect the 

 larval state only is intended; if a f, the pupal. When these follow the other sym- 

 bols, A or C, it is to be understood that all states occur, advilts preponderating. If 

 they precede the letter, all states occurred in numbers indicated. Thus A * f , adults 

 abundant, larvae and pupae; * f C, all stages common. 



List of insects. 



