320 STATE HORTICULTURAL SOCIETY. 



a^o the pest was carried into the Michigan peach district on nursery stock 

 from the east. It seems not to have gained a foothold among the Cali- 

 fornia orchards as yet; the board of horticulture of that state is fully 

 alive to the importance of the pest, and it is on the alert to prevent^its 

 introduction. 



Its classification. — This insect is one of the true bugs belonging to the 

 game family — the Aphididce — as the grape phylloxera, the grain aphis, 

 the hop louse, and many other well known plant-lice pests. Scientifically 

 the insect is known as Aphis persicce niger — the Latinized form of the 

 common name, black peach aphis. This name was given in 1890 by Mr. 

 E. F. Smith, who after comparing it with descriptions of allied known 

 species became convinced that the species was new and so described it. 

 Mr. Smith believes that the insect is a native species, as he found it com- 

 mon on the roots and branches of the wild plum, Prunus chicasa, thus 

 indicating that this may be its original food plant. 



The appearance of the insect. — The pest appears in two forms, the 

 more common form without wings (Fig. 1.), and a form occurring in 

 limited numbers provided with four ample wings (Fig. 2). The adult 

 wingless insect is a little less than one tenth of an inch in length 

 and of a dark shining brownish-black color with portions of the legs 

 yellowish. Figure 1 shows the shape and general appearance of wing- 



FiG. 1— Wingless viviparons Fig. 2. — Winged viviparous female, 



female. (After J. B. Smith.) 



less form; the hair line at the right represents the natural length of 

 the body. Two very short tubercles called honey-tubes project from the 

 caudal end of the abdomen. The beak lies along the breast of the 

 insect when at rest but when feeding it is placed against the leaf at right 

 angles to the body, and four fine bristles mo dug in a groove of the beak 

 are forced into the tissues and the sap is pumped through this apparatus 

 into the body. 



The adult winged forms have the long transparent wings carried roof- 

 like over the side of the body when at rest. These forms also differ from 

 the wingless ones in being slightly longer and more slender, and in having 

 longer antennae and honey-tubes, as is shown in figure 2; the lines beneath 

 the figures represent the natural size of this form. 



In its younger stages the insect resembles the adult, but is lighter in 

 color. All the forms thus far observed are females; often plant-lice breed 

 freely for many generations or even years without the appearance of males, 

 nothing but the agamic females being produced. 



The life history of the insect. — Plant-lice present more varied, pecu- 

 liar, and interesting phases in their life histories than do most other 

 insects. The mother is often viviparous, that is she brings forth her 

 young alive; the little louse may be seen kicking to free itself from the 



