418 ^A^ INTRODUCTION TO ENTOMOLOGY 



In the Aphidinae the males and the oviparous females are com- 

 paratively generalized; they are furnished with functioning mouth- 

 parts and feed as do the other forms; the females lay several eggs; 

 in a few species the oviparous females are winged; and winged males 

 are common. Wax-glands are not abundant in members of this sub- 

 family ; and the antennal sensoria are oval or subcircular. 



The following are a few of the more common representatives of 

 the Aphidinae. These are selected to illustrate some of the more 

 striking differences in habits exhibited by the different species. 



a. BARK-FEEDING APHIDIN^ 



The following species will serve as an example of the bark-feeding 

 species belonging to this subfamily, and also of the maximum size 

 reached by any aphid. 



The giant hickor}'-aphid, Longistigma cdryce. — This is a ver\- large 

 species, one of the largest aphids known, measuring to the tip of the 

 abdomen 6 mm., and more than lo mm. to the tips 

 of the wings (Fig. 491). It can be distinguished by 

 the shape of the stigma of the fore wings, which is 

 drawn out at the tip to an acute point extending 

 ^% ^^ma^^arTI^' ^^^^t to the tip of the wing. The top of the thorax 

 '^^' and the veins of the wings are black and there are 

 four rows of little transverse black spots on the back. The body is 

 covered with a bluish white substance lilce the bloom of a plum. 

 This is a bark -feeding species; it is found clustered on the under 

 side of limbs in summer. It infests hickory, maple, and several 

 other forest trees. The oviparous female is wingless; the male, 

 winged. 



h. LEAF-FEEDING APHIDIN^ 



Examples of the leaf-feeding species belonging to this subfamily 

 can be found on a great variety of plants. Among those most easily 

 observed are the species infesting the leaves of fiiiit trees, and 

 especially the following. 



The apple-leaf aphis. Aphis pomi. — This is a bright green species, 

 the entire life-cycle of which is passed on the apple. The migrants 

 fly to other parts of the infested tree or to other apple-trees. As a 

 result of the attacks of this species the leaves of the apple are often 

 badly curled and sometimes drop off the tree. 



The rosy apple-aphis, Anuraphis roseus. — The common name of 

 this species refers to the fact that the agamic females are usually 

 of a pinkish color; but they may vary in color to a light brown 

 slaty gray, or greenish black, with the body covered with a whitish 

 coating. This species is most common on apple; but it infests also 

 pear, white thorn, and three species of Sorhus. It is a migrating spe- 

 cies. 



