APPLE INSECTS 149 



them a knotty appearance, thus ruining them for market. 

 Apples dwarfed by aphis injury usually present a characteristic 

 puckered condition at the blossom end (Fig. 159). The rosy 

 apple aphis also helped in this destructive and unusual outbreak. 



References 

 N. J. Agr. Exp. Sta. Bull. 143. 1900. 

 Del. Agr. Exp. Sta. ISth Rept., pp. 130-136. 1902. 

 U. S. Bur. Ent. Circ. 81. 1907. 

 Col. Agr. Exp. Sta. Bull. 133, pp. 23-28. 1908. 



The Rosy Apple Aphis 

 Aphis sorbi Kaltenbach {Aphis ynalifolicB Fitch) 



This species is now widespread and common throughout 

 the United States and Canada. It is probably an old European 

 species which was introduced into America more than half a 

 century ago. Apple is its favorite food-plant, but pear, white 

 thorn and three species of Sorbus are sometimes infested. 



This rosy aphis often occurs on the same trees and in the 

 midst of colonies of the next species, S. avenoe, but it is not so 

 restless and active. The stem-mothers hatched from the hi- 

 bernated shiny, black, oval eggs in early spring, are globose 

 in shape and of a dark purplish-brown color mottled with black. 

 They are thinly covered with a whitish pulverulence and have 

 blackish antennae, cornicles and legs. The progeny of these 

 stem-mothers are wingless parthenogenetic females, usually of a 

 pinkish color, but sometimes varying to a light brown, slaty 

 gray or greenish black with the body covered with a whitish 

 coating. This mealy appearance and its pinkish color will 

 usually readily distinguish the wingless forms of this rosy 

 aphis from those of the other two species. The tips of the 

 antennae and cornicles are black. Another brood of these wing- 

 less viviparous females is developed on the leaves in early 

 June, but the progeny of these, or the third generation from tlie 



