APHIDES. 179 



some of which are cottony, and some have a hairy 

 covering. 



With regard to what we know at present of means 

 of prevention, our best course is, if we can, to nip the 

 evil in the bud by destroying the very first Aphides 

 that appear. This plan is constantly carried out in 

 field management with regard to the Bean Aphis. 

 When the Colliers, as they are called from their black 

 colour, appear on the tops of the Bean shoots (see 

 Fig. 132), these infested shoots are cut off. If the 

 shoots and Colliers on them are destroyed, the attack, 

 or at least a great deal of it, will be stopped ; but if, 

 instead of carrying off the fragments and destroying 

 them, they are only thrown on the ground, the Black 

 Aphides will just walk, or fly, back again to the 

 growing Beans, and the labour will have been in 

 great part lost. 



This same plan is useful throughout the summer 

 for all plants or trees, such as Apple, Plum, Cherry, 

 or others, in which Aphides, or Green Fly, as they 

 are often called, collect in great numbers on shoots, 

 which may be cut off without hurting the plant. 

 Thus, if the shoots and Aphides on them are properly 

 destroyed at once, we get rid of centres from which 

 attack is constantly spreading to do present harm. 

 Also we may thus lessen the amount of next year's 

 attack. It is the autumn brood of males and females 

 which provide the eggs to start the attack of the 

 following year ; and therefore anything which lessens 

 the production of broods is useful. The shoots, how- 

 ever, should always be destroyed at once ; not merely 

 thrown aside to wither gradually, whilst their in- 

 festing hordes gain wings to go home again. 



A healthy, yet not rank, growth is one great means 

 of lessening the bad effects of Aphis attack ; as in the 

 case of other insect attacks, the plant is thus sup- 

 ported through its troubles. But there is a further 

 reason. It has been found that Aphides come to 

 maturity more rapidly where the plant growth is so 



