INSECT PESTS 77 



INSECT PESTS 



Willow Aphides. There are several species of 

 aphides which attack willows, and, on the whole, they 

 are, perhaps, the most serious pest with which the 

 grower has to contend. By sucking the juices of the 

 plants, they stunt and kill both leaves and rods. 

 They also secrete large quantities of honey dew which 

 falls on the leaves, coating them over with a kind of 

 varnish, and greatly accentuating the damage done by 

 the insects themselves. Further, a black fungus or 

 " mould," commonly grows on the honey dew, coating 

 the leaves still further, and making it impossible for 

 them to carry out their functions. It should be 

 emphasised that the honey dew is always the product 

 of the aphides, and is not a separate form of blight 

 due to climatic conditions, an opinion which is commonly 

 held but which is quite erroneous. 



It is unnecessary here to enter into the features by 

 which the various species are distinguished, and, in 

 many cases, their habits require further investigation. 

 It may, however, be mentioned that certain common 

 species (Siphocoryne caprea and S. pastinacecz) live 

 partly on the willow and partly on weeds such as 

 hemlock, wild parsnip, chervil, angelica, etc. (Umbel- 

 lifer at), and special attention should, therefore, be paid 

 to the eradication of such weeds. 



Species of Aphis common on the leaves and shoots 

 are Aphis saliceti, the two species above mentioned, 

 and Pterocoma pilosa. The most common species on 

 the rod itself is Melanoxaniherium salicis. 



Willow Beetles (Phyllodecta vitellinte.P. vulgatissima). 

 In the adult state these insects are shining dark 

 green or blue beetles. They first appear in spring 



