196 



INSECt PESTS 



Indeed it is quite a mistake to suppose that aphids are just 

 aphids whatever plant is in question. There are hundreds of 

 different species, each favouring its own particular plant. 

 When we add the closely related Psyllidm or Plant Suckers, 

 the list alone is formidable enough, but as soon as warm, moist 

 and still weather arrives, their incredible powers of reproduc- 

 tion become well-nigh appalling. 



1. Corn Aphis, 

 a. Ditto, attached by 

 Plagiator Fly. 



3. Cabbage Aphis. 



4. Lettuce Aphis. 



5. Ditto, vroolly-tailed 



variety. 



Plate 44. 

 Aphides. 

 Lettuce Aphis in soil. 

 Bean Aphis or Collier 

 Blight. 

 Ditto, winged form. 

 Hop Aphis attacked by 

 Lady -bird larva. 



10. Apple and Pear Aphis. 



11. Ditto, winged form. 



12. Woolly Aphis, winged 



form. 



13. Ditto, wingless form. 



14. Plum Aphis. 



15. Rose Aphis. 



Growers and human beings in general would stand little 

 chance of continuance on the earth if the Aphide family were 

 not itself controlled by the great Nature balance which asserts 

 itself sooner or later. Uncongenial weather and hordes of 

 parasitic flies thin their ranks constantly, but the gardener 

 and particularly the flower-lover have to take action on their 

 own account, the farmer being usually compelled to let things 

 take their course. 



The commonest kinds of aphids with which we have to deal 

 are the Corn, Cabbage, Lettuce, Bean, Hop, Apple, Pear, 

 Plum, and Rose, which are shown on Plate 44. 



