224 ECONOMIC ENTOMOLOGY. 



which contains many species, many of them only too well known 

 to most of us, like the Hop-fly [Aphis hutnuli). There are various 

 species peculiar to certain fruits and plants. Indeed, each fruit 

 seems to have its special aphis. Thus, we have the Apple Aphis 

 {A. malt), the Plum Aphis {A. prttni), the Currant Aphis {Rhopa- 

 losiphiwi j-ibis), and many others. Mr. Whitehead writes of the 

 Apple Aphis : — 



" The Apple Aphis, or Green Fly (by which appellation it is 

 better known), derives its food solely from the juice of the leaves 

 and blossoms. It makes its appearance as soon as the buds begin 

 to swell and the leaves show signs of coming forth, and it follows 

 up the blossoms from their earliest development. The aphis 

 attacks the blossoms, being specially attracted by their saccharine 

 qualities, and either prevents the process of fructification or so 

 besets the tiny fruits that, weakened by the extraction of their 

 juices and begummed with viscous honey-dew, they are unable to 

 set properly. The fruit that perchance survives rarely attains to 

 full size, shape, or quality. As the leaves come out, their under 

 surfaces are occupied by the aphis, and soon curl up, get black, 

 and fall off, leaving the trees bare, and emitting a sickly smell 

 from all sides." 



The aphis is one of the main causes of apples falling imma- 

 ture from the trees, and also largely affects the quality of the cider 

 in certain seasons. This species is found all over the world. 

 The Americans, however, claim that the pest was introduced in 

 their orchards by trees brought from Europe. Another species 

 very injurious to orchards is known as the Woolly Aphis, or Ame- 

 rican blight {Schizonema lanigerd) Everyone who has closely 

 noticed apple-trees will have frequently remarked knots or bunches 

 of a downy or woolly substance on parts of the stems and in 

 interstices of the bark. This is very frequently supposed to be a 

 form of mildew, but if closely examined it will be found that this 

 woolly substance covers little groups of aphides, all actively 

 engaged in extracting the sap. This form is specially liable to 

 attack newly-pruned trees if the cutting has been done carelessly. 

 Old and neglected orchards, of which there are too many, are the 

 special home of this pest, the lichenous and moss-covered stems 

 exactly suiting it and enabling it to remain unsuspected, while the 



