102 INSECT PESTS 



insects and each has its own species, the best known being the 

 Rose Aphis {A. rosce), green in colour and about -c^^ inch in 

 size. The quassia spray is the best argument with which to 

 meet its attacks. 



Fruit is of course productive of special kinds of Aphids, 

 which, with their cousins the Suckers, are responsible for much 

 loss of vigour in both bush and standard trees. 



In the Apple Aphis {A. mali) the queens or stock-mothers 

 are dark grey, the winged and active forms being green with 

 black heads. The Plum Aphis {A . pni7ii) is green at first and 

 then dark grey when fullgrown. Both kinds have been known 

 to feed on either tree, but they usually keep to those whose 

 names they bear. 



Two-wing flies, Lacewings and Ladybirds attack these 

 aphids (see Plate 15), and are of great assistance in preventing 

 their attacks becoming dangerous in the following season, 

 but wherever the twisting and withering of fruit-tree leaves 

 indicates aphis trouble the spray must be kept vigorously at 

 work. Lime-washing in spring also destroys the eggs which 

 are laid all over the bark. Contact insecticides of quassia 

 or nicotine must be used after the blossoms have fallen and in 

 time to prevent the leaf-curl happening. 



Neither of these aphids above mentioned should be con- 

 fused with the Woolly Aphis, which has been dealt with on 

 page 76, and is a different insect entirely, though often as 

 harmful as the two together. It is more abundant where 

 trees have been neglected and attacks both root and branch, 

 and the alkaline winter wash is necessary when the leaves have 

 fallen. 



Aphis queens are the most prolific of all creatures, as 

 although the egg is large in comparison they keep on producing 

 them. But in addition to this it has been found that poly- 

 gamy is practised, a most unusual trait among insects, where 

 one mating usually exhausts the male. 



These quahties, added to the ready changes of form by which 

 they adapt themselves to varying temperatures and inter- 

 mittent food-supply, render it essential that no crop should 

 ever be allowed to fall into a neglected state, so that watch- 

 fulness against aphides early in the season is a duty to our- 

 selves as well as to our neighbours. 



i 



