APHIDS INJURIOUS TO ORCHARD FRUITS. 5 



Since frequent reference must be made in the following pages to 

 the different stages and forms of aphids, information concerning 

 these is presented in summary form as far as present purposes 

 require : 



Winter eggs. — These are small, oval, and blackish, and occur on 

 the twigs, around buds, under scales of bark, or elsewhere on the 

 shoots or branches of the w^inter host plant. 



SteTTh-mothers. — The aphids hatching from the winter eggs. They 

 are the progenitors of the numerous generations which follow during 

 the succeeding spring, summer, and fall. 



Wingless viviparous females. — Wingless aphids which give birth 

 to living J^oung without the intervention of males. 



Winged viviparous females.^ or irdgrants. — Wingeci aphids which 

 give birth to living young without the intervention of males and 

 which migrate to other plants, establishing new colonies. Spring 

 migrants and fall migrants are often to be distinguished. 



The true sexes. — Males and sexual females are usually developed 

 in the fall from the viviparous forms, the female depositing eggs to 

 carry the sj^ecies over the winter. 



APPLE APHIDS. 



Three or four species of aphids commoniy attack the fruit and 

 foliage of the apple, while a few more, wdiich at present are of minor 

 importance, are known to infest this plant. The important species to 

 be considered are the rosy aphis, the green apple aphis, the woolly 

 aphis, the oat or European grain aphis, and the clover aphis. 



THE ROSY APmS.i 



The rosy aphis infests especially the foliage surrounding the blos- 

 som or fruit clusters, and causes the leaves to curl badly. (Fig. 1; 

 fig 2, h; illustration on title-page.) The insects when abundant 

 also infest the fruit stalks and newly set fruit. The little apples on 

 the infested fruit spurs often fail to thin out, remain small, and as 

 the season progresses become knotty and distorted according to the 

 degree of infestation. In the fall these " aphis apples" (fig. 3) may 

 be much in evidence, especially on the lower parts of the tree, during 

 worst aphid seasons amounting to from 15 to 30 per cent of the crop.. 

 This species is very generally present in the apple-growing portions 

 of the country and is at present the most important aphid pest attack- 

 ing the foliage and fruit of this crop. On very young trees the feed- 

 ing habits differ somewhat in that in addition to the foliage the 

 aphids may attack the 3'oung shoots, causing these as they grow to 

 become curled and twisted (fig. 2, c; fig. 4), resulting in permanent 

 deformities which in pruning must be cut out in order that a prop- 

 erly formed tree may be produced. 



Mp/ijs mnlifoliae Fitch. 



