384 



lyisect Pests. 



from them becomes a black, sticky mass, and this damages the 

 leaves below them as well as the fruit. 



In colour this aphis is pale green with deeper green mottlings, 

 and a dark median stripe, and is covered with white meal. They 

 cluster close together under the leaves until a whole leaf is smothered 

 by them. Then winged viviparous females are produced of a bright 

 yellowish-green with dark green markings on the thorax, and tri- 

 angular ones on the abdomen, and with red eyes. They are covered 

 with a certain amount of meal. These winged females fly from tree 



to tree. 



In the early autumn they 

 usually all disappear from the 

 plums. Unfortunately, we do 

 not know anything definite re- 

 garding the life-cycle. Walker 

 stated that it is the same as the 

 aphis found on reeds, etc., known 

 as Ilijaloptcrus arundinis, and I 

 am inclined to think the two 

 are the same. Buckton does not 

 think this likely. I liave never 

 been able to detect any sexual 

 generation on plums, and have 

 always noticed that they sud- 

 denly disappear from the prunes 

 in late autumn. De Geer, how- 

 ever, stated that he found this 

 aphis on an apricot and de- 

 scribes both winged male and 

 Avingless female, and that in 

 September he found an egg with 

 a woolly coat fixed near a leaf bud. 



This may have taken place, but it is certainly not the usual 

 habit. We may safely say that the Mealy Aphis comes to the prunes 

 in summer and leaves them in late autumn. The specimens sent 

 from Scotland were winged and wingless females and pupee. The 

 winged females were viviparous and their young were deposited on 

 prune leaves and reproduced young again and then died off; no 

 sexual brood occurred. 



It has also been found on the peach and nectarine, and in Italy 

 has been observed on grape vines. 



It is usually worst on Victorias and Czars, but it may also occur 



FIG. 250.— THE 3IEA 

 (Hi/alopterus prui. 



[F. Edenden. 

 .\ PLUM APHIS 



/) Oil leaves. 



