321 



October 21, 1863. 



The President in the chair. 



The following communication was presented : — 



Notes on Selandkia cerasi Harris, as it occurs at Ann 

 Arbor, Michigan. By Professor Alexander Winchell. 



[Condensed, with a few additions, from a paper read be- 

 fore the Michigan Scientific Association, June 24, 1863.] 



This destructive insect made its first appearance at this place in 

 1859 : its depredations were, however, not generally observed till 

 1862, when it caused the death of many fine cherry-trees. Its in- 

 creased ravages during the present year have attracted general atten- 

 tion, and induced the writer to extend his observations previously 

 begun, and to determine what relations exist between the Michigan 

 insect and that described by Peck and Harris. 



The fly commenced to deposit its ova the present year on the 5th 

 of June. It selected for this purpose the leaves of the pear and 

 cheny ; though, in the course of the season, it was observed that the 

 mountain-ash and the plum had also suffered to a limited extent. The 

 ova were deposited through rectilinear incisions in the epidermis of the 

 upper side of the leaf; and the chlorophyl, for a small distance 

 around each egg, was changed to a brown color, and deadened, giving 

 the leaf, where the eggs were numerous, a strongly mottled appearance. 

 Trees in open situations were most infested ; and the outer portions of 

 the foliage of a tree were preferred to the more shady. 



The ovipositor is attached at a distance of .025 of an inch from the 

 extremity of the body of the female. "When at rest, it is lodged in a 

 slit which reaches nearly to the tip of the abdomen. It has the form of 

 a butcher's knife, a little bent upwards near the point. Toward the 

 other extremity, the organ is curved in the opposite direction into a 

 right angle with the main axis, and is furnished internally with a 

 couple of apophyses for the attachment of the muscles which move the 

 instrument in the execution of its office. The upper margin of each 

 blade is worked into a series of low, sharp teeth, turned from the 

 point of the blade ; the lower side is furnished with a series of erect 

 teeth, whose margins are themselves serrate. The muscular action 

 which moves this instrument thrusts it entirely through the leaf, cut- 

 ting with the serrated teeth of the lower side as it enters In the act of 

 being drawn ; while the backward turned teeth of the upper margin 



PKOCEKDINGS B. S. N. H. — VOL. IX. 2'i FEBRUARY, 18C5. 



