238 HEMIFTERA-HOMOPTEEA.. 



some send out little bud-like growths from the thorax, rudimen- 

 tary wings, a pupal stage, and from these active pup« come 

 forth winged females, which fly oif to other plants. These 

 winged females are also viviparous, and produce again asexually 

 living young, and so on until the autumn, when a third kind of 

 female appears, the oviparous female, and also a male. After 

 the male has fertilised the female aphis, she deposits a few eggs 

 upon the plants, which remain over the winter. These eggs 

 mostly hatch out in the spring. But many Dolphins also hiber- 

 nate as queen or mother females, and commence to reproduce at 

 once on the return of warm weather. There is often not much 

 difference between the young (larvae), or lice, as they are called, 

 and the viviparous female, but larva, pupa, and adult may 

 generally be distinguished by variations in colour. Some 

 Aphides produce galls which are always open (SeMzoneura 

 ulmaria, S. spirothecce) , others live underground [S. lanigera 

 and Pliylloxera devastatrix). 



The three chief groups are the AplMinm, which have the 

 third vein of the front wmgs twice forked ; the Schizoneurirm, 

 which have this vein once forked ; and the Cliermisince, which 

 have this vein absent. 



Hie Bean Aphis, Black FJy, or CoUier i^Aphis rumicis). 



A common bean infestation is that caused by one of the plant- 

 lice, known as the " Collier.'' This aphis appears first when the 

 beans come into blossom, and especially blights broad-beans. 

 These Colliers collect on the heads, where they breed rapidly, 

 cover the plants with a black sticky mass, and, if they spread 

 down low, quite spoil the crop. These plant^lice are black in the 

 wingless female state The winged females are sometimes rusty- 

 brown, with green honey tubes, but more usually they are quite 

 black ; the male is black and winged ; the young dark-grey to 

 black; and the pupse slaty-grey, with black wing-cases and 

 white spots and patches on the black abdomen. They are also 



