264 HEMIPTERA-HOMOPTEEA. 



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 some Dolphins also 

 hibernate as queen or mother females, and commence to repro- 

 duce at once on the return of warm weather. There is often 

 not much difterence 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 structure 

 and colour. Some Aphides produce galls {Scliizoneura ulmi, 

 Pemjihiiiux spirothecci}, Cherines ahietis, &c.) ; others live under- 

 ground (S. laniijwa and Phijlluxeiu devastatrix) ; others live in 

 ants' nests. The life-cycle of Aphides is often very complex. 

 Most have two or more host plants between which they migrate. 

 The Hop Aphis, for instance, winters in the damson and flies to 

 the hop for the summer ; the Elm Leaf Aphis {Schizoneura 

 ulmi) flies to the roots of Eibes ; the Mealy Plum Aphis 

 {HyalopteriLS pi'uni) to rushes and water grasses. 



The three chief groups are the Aphidinn', which have the 

 third vein of the front wings twice forked ; the ScMzoneuriiue, 

 which have this vein once forked ; and the CJiermisina', which 

 have this vein absent. 



The Bean and Poppy Aphix, BJark Fly, or Collier 

 (^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 



